DDR ram   











DDR Ram Guide

Date: 21.12.2001
Updated: 08.10.2002


DDR memory is getting popular now. However, it is rather hard to know the overclocking limits before buying. Thus we came up with this DDR ram guide. This guide is designed to test the limits of DDR modules on the market and we will update it as time changes.

Before we being, let's have a look at the terminologies.

Name(s) Modell FSB Speed DDR Ram speed Name(s)
SDRAM66 PC66 66 MHz 64 Bit 0.5 GB/s
SDRAM100 PC100 100 MHz 64 Bit 0.8 GB/s
SDRAM133 PC133 133 MHz 64 Bit 1.06 GB/s
DDR266 PC2100 133 MHz 64 Bit 2.1 GB/s
DDR266-Dual PC2100 133 MHz 64 Bit 4.2 GB/s
DDR333 PC2700 166 MHz 64 Bit 2.7 GB/s
DDR333-Dual PC2700 166 MHz 64 Bit 5.4 GB/s
DDR400 PC3200 200 MHz 64 Bit 3.2 GB/s
DDR400-Dual PC3200 200 MHz 64 Bit 6.4 GB/s
RDRAM 400 PC800 400 MHz 16 Bit 1.6 GB/s
RDRAM 400-Dual PC800 400 MHz 16 Bit 3.2 GB/s
RDRAM 533 PC1066 533 MHz 16 Bit 2.1 GB/s
RDRAM 533-Dual PC1066 533 MHz 16 Bit 4.2 GB/s
RDRAM 600 PC1200 600 MHz 16 Bit 2.4 GB/s
RDRAM 600-Dual PC1200 600 MHz 16 Bit 4.8 GB/s

The DDR convention is used to mention the speed of the ram is running. The PC convention is used to denote the bandwidth the ram provides. Okay, enough is enough; let's have a look at the candidates.

PC-2100 (DDR-266) Group

Corsair ValueSelect PC-2100 Cas 2.5 (Super Man Ram??)


Corsair realises that not everyone are willing to pay the premium for the XMS range thus they also have the ValueSelect range. The ValueSelect range is, from Corsair, "Low Cost Memory Solution for price-sensitive applications." I never like the idea of "value" range from my previous encounters with other firms, as they often perform poorly and come with not-so-cheap price. However, the ValueSelect ram is one of the cheapest PC-2100 ram on the NZ market, 15~20% lower than the average ones. This grabs my attention as it is really cheap. We will see how it performs in the benchmark section.

The chip used is rated at 7.5ns which translates to 133 MHz (or 266 MHz) theoretical operation. I can not identify the maker of the chip, an S in the middle. Maybe Superman is the brand?

Update: Various readers have commented that the ram is made by SpecTek who is a part of the Micron Technology family.


Crucial PC-2100 ECC Registered


We can see this stick uses Micron chips. Now, Crucial with Micron chips had always been a HOT commodity in overclocking society. They've been rumoured to hit 180 MHz mark despite being a PC-2100 module.

Please note: You CAN NOT mix registered ram with normal unbuffered rams. It is also adviced that you use registered ram if you are planning to have more than 3 sticks in the system to ensure maximum system stability.


Kingston ValueRAM PC-2100 CL2.5


Kingston is a well-know name in memory industry. They produce some of the highest quality products on the market. The ram chips used in this module is made by Nanya, rated CL=2.5 at 133MHz. I really look forward to test this module since my old Kingston SD-RAM had a good overclocking potential.


PC-2100 (DDR-266) Group

TwinMos PC-2100 CL2.5


The recent surge in DDR price had deterred many from moving to DDR platform or getting high-speed DDR-333 ram modules. Instead, many are looking at low price ram modules and hoping to hit high FSB marks. TwinMos PC-2100 is exactly the sort of ram people are looking for. This ram is said to have a good overclocking potential with relatively low price. However, I "had" concerns with its potentials after seeing its ram chips, elixir, a company I have never heard of. We will see how it performs in the later section.


PC-2400 (DDR-300) Group

Kingmax DDR-300


Tiny BGA is used for this DDR-300 module. The ram is rated at 6ns which translates to 166.67Mhz operation. However, this is theoretical rating only; the actual operational frequency may vary under different conditions. Interestingly, the ram is rated at CL-3 however, DDR only have two ratings 2 or 2.5. Go figure.


PC-2700 (DDR-333) Group

Corsair XMS PC-3000 CL2 V1.1


Corsair XMS range has always been praised as the HIGHEST quality ram available on the market, same goes to price. The improvements over V1.0 are the addition of heat spreader and utilisation of higher density chips. The heat spreader is more of a cosmetic addition rather than a function one, unless you are driving this stick with 3V+ voltage. Corsair used some sort of thermal glue/conductive tape to attach the spreader. I could not get it off the ram with a reasonable amount of force thus there is no picture of the ram chip. The ram chip has a density of 256Mbit therefore only 8 chips is need for 256MByte capacity. This is great news for I845D users, who are short on memory banks, as it is classified as single bank ram instead of dual banks, unlike most 256MByte module.

Note: Corsair guarantees that this module can run at 166 MHz with 2-2-2 setting and 185 MHz with 2.5-3-3 setting.


Crucial PC-2700


Back in Feb 2002, our Crucial PC-2100 ECC Registered lived up to its fame and achieved an astonishing 187 MHz operation (2.5-3-3). Today, we are going to see if Crucial can continue the tradition.

The memory chip used is still made by Micron technology. However, it is rated at 6ns instead of 7.5 for PC-2100 modules. This module is rated at CL-2.5 when running at 333 MHz.


PC-2700 (DDR-333) Group

Kingmax DDR-333

Kingmax is one of the first manufacturers to introduce DDR-333 modules, along with TwinMOS. Let's take a look at some pictures first.


We were unable to obtain more information on the ram, as ctSPD's Memory Readout Utility does not work with DDR ram. We can see the ram is rated at CL 2.5 under 166/333Mhz operation. The chip used in this ram is rated at 5ns which translates to 200Mhz operation. We will see if that is possible in the benchmark section. The layout on the DDR-333 is a bit different from the previous generation; maybe this is done to improve the electrical signal under high operating speed.




TwinMos PC-2700 CL2.5 Version


TwinMos is one of the first companies to release a PC-2700 ram. However, there are two types of PC-2700 release by TwinMos. The first one, the fastest one, is the CL2.0 version using Nanya chips. The one we got is the lower rated one, CL2.5, using Hynix chips. We will see if we could get the one with Nanya chip. Hynix is the former Hyundai, they merged with LGS earlier in the year. A quick visit to Hynix revealed it is only rated at 133 MHz, Cas 2. TwinMos might have hand picked the chips that can operate at 166/333 Mhz.


Samsung PC-2700


Samsung TCB3 PC-2700 memory chip had attracted quite a bit of attention in the past month or so. This is due to their high overclockability and low prices. It is perhaps one of the lowest priced PC-2700 modules on the market. The stick we've got is built on Samsung PCB which is said to have the highest overclocking potential. This PCB's layout is designed for single side operation as the back of the PCB has no "traces". In my experience, single side ram modules always offer better overclocking than the double-sided counterpart.

Note: It's been reported by our reader that the earlier batch of the CTL-CB3 offers a better overclocking potential than the current batch, DTL-CB3. Unfortunately, we can not obtained a sample for test at the moment, as they were sold out long ago. Here are some links to provide the experiences that people have: 1, 2, 3.


PC-3200 (DDR-400) Group

A-Data PC-3200


Back in the early days of PC-2700, we had Samsung CTL-CB3, which was an incredible overclocker. It was used on practically all of the high-end modules. In the PC-3200 age, the WinBond BH-5 chip seems to be the next CTL-CB3. (Corsair are using this chip, hand picked, for their XMS-3200 module)

From the pictures above, we can see that A-Data also uses the WinBond BH-5 chips on their PC-3200 range. From the datasheet, the HB-5 is rated at DDR-400 with a voltage of 2.6V. This is a good sign, as some DDR-400 modules require 2.8V to operate. We shell see how it performs in the following tests.


Corsair XMS-3200


With the release of KT-400 chipset, DDR-400 modules will be the hot pick of the month. Thus Corsair has release a new wave of XMS modules. From their PDF, the newly released XMS-3200 is in line with JEDEC's DDR-333 speed. (Overclockers do not give a toss about it.) Corsair advertised that the XMS-3200 is guaranteed to run at 400 MHz with 2-3-3 1T setting. We will find out if the claim is true or not in the following benchmark section.

Unlike the XMS-3000 which uses Samsung TCB3 6ns chips, XMS-3200 uses Winbond W942508BH 6ns ones. To be honest, I am a bit sceptical at this point since my old OEM Winbond PC-133 did not make it past 140 MHz. However, knowing Corsair, I am sure that the XMS-3200 will perform up to its advertised speed.


PC-3200 (DDR-400) Group

Kingmax DDR-400


As with the DDR-333 case, Kingmax is the first company to release the DDR-400 memory modules. We can see from the sticker that this module is rated at CL 2.5 at 400MHz operation. The ram chip used is rated at -5ns which translates to 200MHz theoretical operation.


DDR 333 DDR 400

The DDR-333 and DDR-400 modules have similar layout. This makes us wonder if Kingmax "hand-picked" the best performing modules and mark them as DDR-400.

It is worth noting that the PC refuses to POST at 200MHz while I left the DDR voltage at 2.55V (default). However, the machine POSTed and got into Win2K when the DDR voltage is raised to 2.85V.



Test Rig

Abit KR7-R Motherboard
AMD XP-1600+ CPU
Maxtor DM60 plus 30GB ATA100 Hard Drive
Leadtek WinFast GeForce2 Ti 64MB Video Card




Above is the BIOS screen shot for the RAM setting used for testing. All the settings remained constant through out the test, only Cas Latency, Trp, and Trcd were changed to test the ram under different settings.

As the DDR-333 and DDR-400 modules appear on the market, our Abit KR-7A motherboard seems to be a bit dated due to lack of PCI dividers (max at 1/4). We will be looking at upgrading the test bed in the future to accommodate high FSB.

For all the tests, DDR voltage was set at 2.85V instead of default 2.5V. This is done to find the maximum overclocking potential of the ram. As long as one keeps voltage under 2.9V, the ram module should be safe.

For the Kingmax modules, we tested under 2.5/2.85V and found out they performs BETTER under high voltage, i.e. 2.85V. This is very interesting to see as www.overclockers.com found Kingmax modules have a better performance with default voltage.

Definition of stability: The machine will boot into Windows (obviously), finish 1 run of Sandra 2001 memory benchmark, 1 runs of 3D Mark 2000, 1 runs of 3D Mark 2001, and 1 run of Super Pi 1M calculation.



The following table shows the maximum FSB with respect to each setting for each ram module.


Group Ram Module 2-2-2 2.5-3-3 Max overclocking % from default
DDR 266 Crucial DDR-266 172 187 40.1%
Corsair PC-2100 162 170 27.8%
TwinMOS PC 2100 152 166 24.8%
Kingston PC 2100 138 150 12.8%
DDR 300 Kingmax DDR-300 158 162 8%
DDR 333 Corsair XMS PC-3000 180 195 20%
Crucial PC-2700 176 190 14.4%
TwinMOS DDR-333 150 190 14.4%
Kingmax DDR-333 175 187 12.7%
Samsung PC-2700 175 191 15%
DDR 400 Kingmax DDR-400 179 200 NA
Corsair PC-3200 200 NA NA
A-Data PC-3200 195 200 NA
More is coming

DDR -266 (Crucial DDR-266 is our top pick)

The Crucial lived up to its name. Despite being a PC-2100 module, it offers overclocking potential that rivals PC-2700 modules.

The Kingston has a rather disappointing result, 138MHz at 2-2-2 setting. This ram is not for overclockers.

The TwinMos lived up to its name, offering a 24.8% overclocking potential. This ram would be the ideal choice for people on a budget.

Wow, the ValueSelect ram performs flawlessly at 162 MHz with 2-2-2 setting. This is the best overclocking ram I've seen at this price range. For the price sensitive people, you can not go wrong with this stick, 162 MHz with 2-2-2 and 170 MHz with 2.5-3-3. I challenge anyone who can come up with a better choice at its price.

DDR -300

The Kingmax DDR-300 has similar max FSB regardless of the memory timing. Generally speaking, reducing the memory timing would give around 5~10 Mhz more. Maybe we have reached the limit for that module.

DDR -333

The Kingmax DDR-333 certainly offers a good potential for those high FSB seekers. It can do 175 at 2-2-2. I don't know about you but to me it's damn impressive. It provides a very healthy memory bandwidth to your system as well.

The TwinMos module performs badly in the 2-2-2 setting, sporting 150 MHz. Anything higher than that would result in lock up in POST. However, the ram performed flawlessly in 2.5-3-3 mode, sporting an astonishing 190 MHz, the highest FSB yet.

Corsair XMS-3000 achieving an astonishing 180MHz at 2-2-2 setting and a new height of 195MHz at 2.5-3-3. Overclockers, this is THE ram to get. You can't go wrong with this module.

It is a bit disappointing to see that Crucial PC-2700 is only slightly better than the old PC-2100 Registered counterpart. I was hoping that this module could break the magical 200 MHz barriers. With the above said, Crucial PC-2700 is still a good ram module, offering good overclocking potential. It is only overshadowed by the Corsair XMS-3000.

Samsung PC-2700 is able to achieve a high operational frequency of 191 MHz at 2.5-3-3 setting. Its performance is just shy of our current king, Corsair XMS-3000. It should not be surprising as they both used the same chip, Samsung TCB3. However, Corsair handpicked the top batches. Overclockers on a budget should consider it as a good substitute for the XMS-3000.

DDR -400

A-Data performed admirably, 195 MHz at 2-2-2 timing. I believe that this is the first time a "budget" module can reach such a MHz. Again, I did not test any FSB greater than 200 MHz due to the limitation of Abit's KR7A. This module would be a perfect substitute to Corsair XMS-3200 for the overclockers who are on a budget.

Well, the Kingmax DDR-400 module failed to impress me with 2-2-2 setting. It is even worse than the Corsair PC-3000 module. However, it truly shines in high FSB, reaching an astonishing 200MHz on our KR7A. At that speed, it may well be that our board is holding back the ram. We will be doing a retest in the future when official DDR-400 chipset hit the market. For the time being, this module offers the highest FSB, 200MHz, we ever achieved on this test bed.

Ladies and gentlemen, we have a new winner here!!! The Corsair XMS-3200 is capable of handling 2-2-2 setting at 200 MHz. This is a big leap from the previous 180 MHz mark. I was unable to test FSB > 200 MHz, as our testing rig, Abit KR7A, will not work properly after 200 MHz. (PCI bus at 50 MHz) We have no hesitation in recommending XMS-3200 to anyone seeking THE best memory on the market.


Corsair XMS-3200 DDR400 RAM A-Data PC-3200 DDR400 RAM


FPS vs increase in FSB

Some users maybe wondering, what is the real-world benefit from high FSB and low Cas rating? I did a few benchmarks and hope they would be able to answer the questions.

Test Rig

- Abit KR7 Motherboard
- AMD XP-1600+ CPU (Always fixed ~1400Mhz +/- 5MHz in the test)
- Kingmax DDR-333 256MB*2
- Maxtor DM60 plus 30GB ATA100 Hard Drive
- Leadtek WinFast GeForce2 Ti 64MB Video Card

I ran Q3D - Demo001 under different ram settings and game resolutions.

640*480*16Bit*Normal Mode

This is the low video bandwidth mode where graphics card should not be a bottleneck.


  2-2-2 2.5-3-3
133MHz 213.40 211.55
140MHz 220.80 217.00
155MHz 232.90 228.00
165MHz 243.30 235.10
175MHz 253.30 242.80




At Cas 2-2-2:
There is an increase of 18.57% in FPS when moving from 133 to 175MHz.

At Cas 2.5-3-3:
There is an increase of 14.77% in FPS when moving from 133 to 175MHz.

You need an extra of 10MHz to make up for lower Cas rating, i.e. FSB of 175 Cas 2.5-3-3 is on par with 165 Cas 2-2-2.

1024*768*16Bit*Normal Mode

This mode is used to simulate what could happen when video card becomes a bottleneck.


  2-2-2 2.5-3-3
133MHz 176.35 175.30
140MHz 178.20 177.35
155MHz 182.50 181.38
165MHz 184.90 183.80
175MHz 187.10 185.80




At Cas 2-2-2:
There is an increase of 6.1% in FPS when moving from 133 to 175MHz.

At Cas 2.5-3-3:
There is an increase of 5.99% in FPS when moving from 133 to 175MHz. The increase is less dramatic compared with 640*480*16*Normal mode. The GFX now becomes the bottleneck since Q3 can only run as fast as the GFX can. Like we said in various reviews, in gaming situation, your system will be as fast as your slowest component, usually the GFX card.

Just out of interest, I repeated the test under 1024*768*32*Quality mode and found virtually no increase in performance.

That's it for now folks. Check back sometime later for results on other modules.




Truths and Misconceptions

Date: 23.09.2002


With today's technology changing so quickly it is very easy to get behind. But when you hear about the fastest memory or CPU you think to yourself, "I have got to have it." Well, in truth, when looking at purchasing DDR based memory, there are a lot of things that you have to take into consideration. I am writing this article due to the fact that I frequently browse hardware forums and sites and one of the more notable questions that comes up all the time is, "What is the fastest memory?" or "What kind of memory should I buy?" People typically reply back and say what the faster modules are, or their opinion of different types of memory. What a lot fail to say are the other interesting points that one needs to know in order to maximize his / her system's performance, and at the same time spend money wisely.

DDR memory is available in a wide variety of different speeds at the moment. Here is a short list of some of the more common types:

  • PC1600 - DDR200 MHz (100x2)
  • PC2100 - DDR266 MHz (133x2)
  • PC2700 - DDR333 MHz (166x2)
  • PC3000 - DDR366 MHz (183x2)
  • PC3200 - DDR400 MHz (200x2)
  • PC3500 - DDR433 MHz (216x2)

Many manufacturers produce these modules, Corsair, Kingston, Samsung, Mushkin, Geil, XtremeDDR, and Crucial just to name a few. Each of these companies produces memory that is "rated" at a certain speed. They stand by their product and claim that the memory will run as fast as its rated speed. As I stated before there are many other factors though. For instance, if you are using a DDR333 motherboard, then your motherboard definitely supports DDR333 or PC2700. Anything higher than PC2700 you will have to overclock to get it to run at that speed. To put it simply, just because you buy PC3500 doesn't mean that you will be running 433 MHz (DDR). You have to overclock to that speed because the current standard only supports up to PC2700. To overclock your memory you must raise the front side bus which will typically overclock your AGP/PCI slots, CPU, and DIMM slots. Anytime you overclock, you run the risk of damaging parts or you might have issues with stability and performance of the rest of your system. Selection of memory will be directly influenced by the components in the rest of your system.

The main component that you need to take into consideration is the motherboard. It will have to be able to handle the speeds that you want from your memory. So the first thing to think about when purchasing DDR memory is, "Will my motherboard be able to handle the speeds that I want to run at, and does it provide options in the BIOS that I will need to overclock my memory?" I would suggest reading up on your motherboard and finding out the results that others have had. This is key and will greatly aid in deciding which memory you should purchase.


Choosing Memory For AMD Systems:

Let's start with the AMD platform. When picking DDR memory for an AMD based system you need to be really picky about what you buy. There are very few AMD based motherboards at the moment that can run at DDR400 speeds. Most support 333 MHz but some are just better overclockers than others. The good thing about the AMD platform is that you can unlock the multiplier on the chip. The multiplier x FSB (front side bus) gives you your CPU speed. For instance 133 FSB with a chip that has a 10 multiplier would give you 1,330 MHz (133x10) or 1.33 GHz. Since you are raising the FSB to overclock your memory, your CPU will come into play. It will be getting overclocked and at some point it will not be able to overclock any higher. This could stop you from maximizing you RAM. So by unlocking the CPU and lowering the multiplier, you could run the processor at a speed you know it can handle but overclock the FSB even higher to maximize the memory bandwidth. So let's say you don't want to overclock your CPU but you want to get your memory to run at its maximum, which just happens to be 400 MHz (200FSBx2). Using the same CPU as the one in the first example and considering you have a good motherboard, you could use the 6.5 multiplier and run your CPU at 1.3 GHz (200x6.5). Issues that this high of a FSB are mainly PCI/AGP clocks as they are now running out of specification which cause instabilities, video distortions, or glitches (AGP tearing), hard drive issues, and the list just goes on. Luckily most 333 motherboards provide a 1/5 divider which allows you to put your AGP/PCI closer to spec. At 133 FSB on a 333 motherboard your AGP/PCI clocks run at 66/33. This is uses a ¼ divider for the PCI. At 166  FSB you could use the 1/5 divider to bring your AGP/PCI back to spec, but anything higher will make you run out of spec again. So when trying to run at speeds over PC2700 you might run into issues with your AGP/PCI clocks. In short your video card, hard drives, soundcard, etc. will determine how high you can go as well the memory.

As you can see when running an AMD machine and trying to maximize memory, there are a lot of other issues that that you have to deal with. Major concerns are the AGP/PCI clocks and the CPU speed. Also to really maximize the RAM it's nice to have voltage options up to 3.2 volts on the VDIMM such as the Epox 8K3A. I like AMD machines myself but they just cannot seem to overclock the memory like the Intel Platforms do.


Choosing Memory For Intel Systems:

Picking RAM for an Intel machine is not any easier than picking it for an AMD rig but you can overclock easier in some aspects and harder in other when compared to AMD. Unlike the AMD, Pentium 4 multipliers cannot be unlocked. So you can only overclock the RAM by upping the front side bus and the rest of the system. The good thing is that on an Intel platform you can lock the AGP/PCI clocks in at 66/33, this is a very nice feature that I like. You don't ever have to worry about if your video card, sound card, hard drive, etc. is giving out. Other things like we discussed earlier like voltage options, etc still will play a part in deciding process.

Okay since we cannot unlock the multiplier what can we do to make the ram run faster? Well luckily Northwood P4's are very good overclockers to begin with. They are able to achieve high FSBs on good air-cooling. Also there are options on the Intel platform motherboards such as RAM ratios. For instance, I have an Abit IT7, let's say I can overclock my CPU to roughly 160 FSB with good air-cooling using a P4 1.6A. This would mean the chip is at about 2.56 GHz and the RAM is set at 1:1 (FSB:RAM) so I would be running it like the AMD rig. It would be 160x2 so it would be 320 MHz DDR but my IT7 has a 3:4 memory ratio. So at 160 FSB the memory would be at 213x2 which would be 426 MHz! This is great for people who want to use PC3500 and run some really great memory speeds. Now you run into issues again though. Let's say you have really good cooling for instance. Something that lets you overclock to say 190 FSB. If you were to use a 3:4 memory ratio the memory would be at 506 MHz (253x2). Let's also say that you have some PC3500 that you want to use, well there are not many sticks of RAM that can run at 506 MHz. But if you were to use the 1:1 memory ratio then you memory would be doing 380 MHz. You would be underclocking you memory below its rated specifications. So what do you do? Well you could get a new chip with a bigger multiplier that will overclock to 160's FSB with serious cooling such as a 2.8 with its 21 multiplier. Or you could run your CPU lower than what you max out at so that you can use the 3:4 divider. This is the exact spot I am in at the moment. In my situation I can run my CPU at 193FSB but I have to use the 1:1 ratio. I don't want to go back to a lower FSB because I like my CPU to be maxed out. So what am I going to do? I am going to get a chip with the larger multiplier so I can have super fast CPU speed as well as memory speed.


Conclusions & Other Insights:

So you see there is a lot to Intel platforms as well as AMD. You have some good benefits and some bad for each. You have to choose your RAM wisely considering what kind of chip you have and what FSB you can run. I've seen some people get in a situation where their CPU was a bad overclocker so they could not max out the RAM, so they got extreme cooling and were able to overclock the CPU a lot more but got stuck in the situation that I am in.

When purchasing memory you have to find the perfect balance of everything if you want your components to be running at their full potential. This is called the sweet spot. Both AMD and Intel machines have a sweet spot where you have the perfect balance of memory bandwidth as well as CPU speed.

Now that we have covered the AMD and Intel platforms separately by what each machine has to offer and how it affects your choice, now let's talk about the last thing that applies to both. Memory timings are just as important as overall speed. Some people buy PC3500 and expect it to run at 3500 speeds and forget that not only is there a rated speed, but every stick of RAM has its own memory timings. For instance, some are CAS 2.5 3-6-3 2T and some are CAS 2 3-6-3 1T. These timings will influence how well you can overclock the memory as well. Since this is not a overclocking guide I will not go into what the timings mean but I just want the buyer to keep in mind that his memory is rated to run at a specific speed at specific memory timings, anything faster and you are overclocking your memory just like any other component, which mileage can vary.




DDR Memory Performance Roundup

May 17th 2002


With DDR memory now in the affordable price range, and motherboard manufacturers phasing out SDRAM on nearly every new board, it looks like DDR is definitely here to stay. Even corporate giant Intel dumped the once-all-mighty RAMBUS, and opted for integration of DDR support into their chipsets and motherboards, only to join forces and rise to power with the P4. Memory manufacturers are doing a good job of producing high-quality RAM for demanding systems and the ever-changing industry, but how do you know what's what on the memory front? There are so many different DDR modules available these days, it's hard to know which one will offer the best performance.

DDR Memory Performance Roundup

Tweakers Australia has come up with an article that will address several of these queries, including the different brands and models on the market, how they perform, and how they compare to each other. We'll be starting off with 4 DDR333 sticks and 1 DDR266 stick, and adding more as we get a hold of them. The DDR Memory Performance Roundup will also feature regular updates and new testing procedures when they are available… but for now we'll be checking out the bandwidth and timing of the 5 models we have here today, so lets get started!

What is DDR

DDR memory is the latest in high-performance memory module technological advances. It offers twice the data bandwidth of conventional PC100 or PC133 SDRAM, and is particularly well suited for high-performance servers and workstations, which need optimal CPU-memory performance. Double Data Rate (DDR) SDRAM (AKA SDRAMII) is precisely what the name implies. A clock cycle can be represented as a square wave, with the rising edge defined as the transition from "0" to "1", and the falling edge as "1" to "0". In SDRAM, only one of these wave edges is used, but DDR SDRAM references both, effectively doubling the rate of data transmission. Unlike 168-pin SDRAM, DDR SDRAM utilizes a 184-pin plug. Although the basic motherboard technology does not need to be changed, DDR SDRAM is not backward compatible on motherboards designed for SDRAM.


Not many systems out there run a system bus of 166MHz, so without an overclocked system your not going to benefit from the extra bandwidth DDR333 memory provides, since both AMD and Intel currently make CPUs that only run on a 133MHz bus. A lot of motherboards have a setting in the BIOS which allow you to set a divider that adjusts the DIMM frequency, enabling you to run DDR333 memory in on a system bus of 166MHz, 133MHz and even 100MHz. In my experience, running DDR333 in asynchronous mode doesn't do much at all, as DDR memory can only derive its true speed and bandwidth from doubling the actual system bus in synchronous mode.

For testing I choose ABIT's latest KT333 motherboard - the KX7-333R - for it's stability, and the extensive range CPU and memory settings in the BIOS. I performed four tests on each stick including a 133/133 synchronous bandwidth test, a 133/133 synchronous bandwidth test with more aggressive timings, a 133/166 asynchronous bandwidth test, and a 166/166 synchronous bandwidth test using an overclocked AMD XP1600.

DDR Memory Performance Roundup

The ABIT KX7-333R officially supports DDR333, along with the necessary PCI and AGP dividers. This meant that running the system bus at 166MHz wasn't going to induce any stability issues with the PCI and AGP buses, but running it any higher could potentially cause problems. This is why we will follow up this article at another date with a high-FSB comparison of the modules, using an unlock AMD CPU.

Test System

Processor: - AMD XP1600+ (1.4GHz)
Motherboard: - ABIT KX7-333R (KT333)
Memory: - Apacer PC2100 256MB DIMM
- Apacer PC2700 256MB DIMM
- Kingmax TinyBGA PC2700 256MB DIMM
- Crucial PC2700 256MB DIMM
- OCZ PC2700 256MB DIMM
Storage: - Maxtor 20GB 7200rpm ATA133
Graphics: - PixelView GeForce4 Ti4600 128MB
Sound: - Disabled
Power: - Enermax EG365-VE(FMA) Dual Fan PSU
Case Info: - None
Software: - Windows XP Professional
- SiSoft Sandra 2002

Apacer PC2100

Established in 1997, Apacer is a young and rapidly growing company within memory industry. With a global reach of more than 1000 distributors worldwide, Apacer Technology Inc. stands firm as one of the industries market leaders. According to Dataquest in 1999, Apacer is amongst the top five third party memory module companies worldwide.

DDR Memory Performance Roundup
DDR Memory Performance Roundup
DDR Memory Performance Roundup

The Apacer PC2100 module features 16x NANYA memory chips, each rated at 6ns. The DIMM is double sided, and the CAS Latency of the DIMM is rated at 2.5.

DDR Memory Performance Roundup

Apacer PC2700

Apacer was one of the first RAM manufacturers and offer PC2700 DDR333 memory for the consumer market. The Apacer 256MB DDR333 module is rated at CL2.5, and features Samsung memory chips rated at 5ns. The module is designed with memory chips on one side only.

DDR Memory Performance Roundup
DDR Memory Performance Roundup
DDR Memory Performance Roundup

DDR Memory Performance Roundup

Kingmax PC2700

Founded in 1989, Kingmax Technology Inc. is a leading manufacturer of PC peripheral products in Asia. Manufactured with high quality components to strict engineering and quality standards, Kingmax manufactures and designs virtually every kind of PC Card, memory upgrades and networking devices. Kingmax Semiconductor Inc. is the first in the world to introduce the patented TinyBGA package technology which drastically reduces the size of the chip itself and increases the overall electrical and thermal performance of the DRAMs.

DDR Memory Performance Roundup
DDR Memory Performance Roundup
DDR Memory Performance Roundup

The Kingmax DDR333 PC2700 256MB 184-pin unbuffered DIMM is packaged with TinyBGA technology, and uses a DRAM die geometry process of .15um. The advanced TinyBGA package technology drastically reduces the size of the chip itself and increases the overall electrical and thermal performance of the SDRAM component. Kingmax was also the first manufacturer to release DDR333 memory.

DDR Memory Comparison Guide

Crucial PC2700

Crucial was one of the last manufacturers to offer PC2700 to the consumer, but the reason behind this was so they could be approved by JDEC for the DDR333 standard. Crucial Technology is a division of Micron Semiconductor Products Inc, a wholly owned subsidiary of Micron Technology Inc. Located in Boise, Idaho, Micron manufactures dynamic random access memory (DRAM) chips and assembles them into memory modules for the global computer industry. Currently, Micron is the only DRAM manufacturer in the US and one of the three largest in the world. Micron is one of the top suppliers of memory to the major original equipment manufacturers (OEMs) including Compaq, Gateway, micronpc.com, HP, and IBM. Crucial conducts 94% of their sales over the Internet, and is the consumer orientated sister company of Micron.

DDR Memory Performance Roundup
DDR Memory Performance Roundup
DDR Memory Performance Roundup

The Crucial PC2700 256MB modules features 16 Micron memory chips, each rated at 6ns. By cutting out the middle man by choosing to do business over the Internet, Crucial also offers some of the most cost-effective modules on the market.

DDR Memory Performance Roundup

OCZ PC2700

OCZ Technology has been criticized in the past for 'faking' faster memory just to get their modules out onto the market before anyone else does. Other sources say that they provide select hardware review sites with faster-than-actual sticks, for the purpose of achieving higher scores in benchmarks. I have no personal ill-feeling towards OCZ in any way, and up to date they have been consistent with producing high quality memory modules incorporating some of the best chips from Micron and Samsung. The module we received comes with a copper heatspreader on either side, which made it very difficult to take snaps of the memory chips themselves.

DDR Memory Performance Roundup
DDR Memory Performance Roundup
DDR Memory Performance Roundup

DDR Memory Performance Roundup

Bandwidth comparison

The following graphs show a comparison of the bandwidth figures from each module under each mode. Instead of showing you how high we could clock the memory, I thought it would be interesting to show the bandwidth comparison of the tested modules.

DDR Memory Performance Roundup

DDR Memory Performance Roundup

DDR Memory Performance Roundup

Overall the best three modules were the Crucial PC2700, the Apacer PC2100 and the Kingmax PC2700. I was disappointed with the performance of the Apacer PC2700, but was surprised with the Apacer PC2100. The Apacer PC2100 delivers excellent performance and ran without any problems whatsoever at 166MHz. As for the OCZ memory, apart from having the best aesthetic qualities it came in second last.

Timing effects

Timing basically refers to the CAS Latency, Precharge to Active (Trp), and Active to CMD (Trcd) settings usually found in the Advanced Options menu within the BIOS. There is much hype about the effects of timing and how it can dramatically increase performance, and the graph below gives a good representation to the impact timing can have. The default timing for all modules was 2.5-3-6-3 with 1T Command Rate and 4-way Bank Interleave, whist the more aggressive settings for the comparison were 2-2-5-2 with 1T Command Rate and 4-way Bank Interleave. Here is a couple shots of the BIOS, with the two different timing setups.

DDR Memory Performance Roundup
DDR Memory Performance Roundup

DDR Memory Performance Roundup

There wasn't one module that had any issues with the more aggressive memory timings, and the extra bandwidth offered from the tweaking is worthwhile. Once again, it looks as if the Crucial PC2700, the Apacer PC2100 and the Kingmax PC2700 enjoyed the timing the most out of the five sticks tested.


In summary, I have to give the performance award to Crucial. They have produced an excellent PC2700 stick, and are one of the few companies that waited until JDEC approved the DDR333 standard. The best value award is going to Apacer for their PC2100 product, which has some great overclocking potential and performs pretty much on par with the Kingmax module at 166MHz. As for looks, the OCZ PC2700 scoops up this one as the only company that includes those cool copper heatspreaders - despite having no effect on performance.

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Copyright © 2002 Øyvind Haugland
Sist endret:  13 januar 2019

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