With the release of the nForce 2, Intel i865PE, and Intel i875P, Dual Channel memory motherboards have finally reached the mainstream. There have been Dual Channel mobos have existed previously, but they haven't been as refined and readily available as they are now. We've covered the technology behind it before, but basically you will get a nice performance boost with a Dual Channel setup over a Single Channel motherboard, CPU speeds being equal.

Currently, the fastest DDR supported by these motherboards is 400MHz, or PC3200. With the release of the TWINX1024-4000, one will have to ask why do we need 500MHz ram? The answer is simple… overclocking. It's no secret that the Pentium 4 2.4C can hit 250FSB without breaking a sweat. Up until now, we've had to run at a 5:4 ratio to maintain stability with our PC3200 modules. We do run our ram a little faster as we pass 250FSB, but stability is questionable as we ramp up the clock speed. Furthermore, since the CPU's FSB and memory speeds are not running in sync, performance is not maximized.

With the Corsair TWINX1024-4000 we'll be reviewing today, we now have an opportunity to run synchronous at 250MHz. Can we go beyond that? We're definitely going to try.

Specifications

Part Number Speed Size Organization Package CAS Latency Memory Type RAM Type Specification TWINX1024-4000 500 MHz 1GB 2x64Mx64 2x184 DIMM 3-4-4-8-T1 Twin Modules 32Mx8 TWINX1024-4000

As the title of the review says, the memory is sold as a kit. We received 2x512MB modules, tested as a pair to insure maximum performance. Here's a bit from Corsair's site:

Corsair's packaging has improved since we've last looked at their TWINX512-3200 kit. Rather than two individually packaged ram modules, we now got both of them in the same package. This of course doesn't really mean much, but it does make it clearer that this kit is a matched pair.

Like past Corsair XMS modules, their ram is encased in black heatspreaders. I'm preaching to the choir here, but heatspreaders have yet to convince me that they effectively cool ram to the point where it will make a difference in overclocking. They do look swank though, and I guess any cooling included won't hurt.

It's hard to demonstrate with a picture, but the heatspreaders are attached to the ram via some frag tape. Not the ideal choice if cooling really matters, but it is less costly than individually applying thermal epoxy at the factory.

A closer look at the modules, and we can see the silver sticker letting you know the specs of that stick of ram. We can see that it's a 512MB stick, rated at 500MHz, with ram timings of 3-4-4-8. As many enthusiasts know, tighter timings (say 2-2-2-6) result in better performance, but as memory speeds increase, it is extremely difficult to maintain stability with such low timings. To be honest, 3-4-4-8 isn't bad at all for 500MHz. Sure, it can be better, and we'll see how we can do with some tweaking.

Overclocking and Stability Testing

Since we're using a 200FSB (800MHz) ABIT IS7-G motherboard, the first thing I wanted to try was what are the tightest timings I could run the TWINX at at 200FSB. After a bit of tweaking, it seems that 2-3-3-5 is about as low as I can go.

200FSB (400MHz) @ SPD	200FSB (400MHz) @ Tweaked

With that out of the way, I did a double check if the ram can indeed handle the 250FSB at 3-4-4-8. One thing I noticed that at the SPD settings, the timings were 3-4-4-7 (as was the case at 200FSB). This was confirmed using CPU-Z, so I guess the ram is slightly tweaked out of the factory.

Next thing we did was to adjust the timings and to see what the TWINX would allow us to tweak to. At 250FSB, the best we managed was…

250FSB (500MHz) @ Tweaked

The ram was completely stable, and passed MemTest without any problems at 2.5-4-3-6. Memory voltage did need a boost to 2.7 though. How about OCing a little further? At these timings...

251FSB (502MHz) @ Tweaked

We only managed to get as high as 251FSB. I managed to get into Windows at 253FSB, but the PC would immediately reboot after. Memory voltage was at the ABIT IS7's maximum, 2.8v, and the CPU was cooking along at 1.8v. We moved the timings back to 3-4-4-8, and gave it another go, but the system would never pass 255FSB. After a few phone calls, and more testing, it has been confirmed by both ABIT and Corsair that the IC7 and IS7 series have a memory FSB issue at 255 and up. ABIT is working on it though, and a fix should be available in the near future.

Obviously, we weren't going to call it a day, so we swapped the ABIT IS7 out, and dropped an Asus P4C800-E in its place. Like the ABIT board, we were able to match the above 200FSB and 250FSB timings, but we weren't able to improve upon them. Our maximum overclock was a different story.

272FSB Max OC

To be able to run your ram 1:1 at 272FSB is simply amazing. When we pushed to 273, MemTest failed, but the system still ran. The TWINX didn't seem to like any timing adjustments at this speed though, as we could never stay stable once we got into Windows.

Just to clear something up, our 2.4C can do in excess of 300FSB using a 5:4 ratio, but that isn't the point here. We are trying to test for the maximum memory OC, and our board does not offer options where the memory can run faster than the CPU FSB.

Test Setup

Asus P4C800-E: Pentium 4 2.4C, 2 x 512MB Corsair TWINX1024-4000, ATI AiW Radeon 9700 Pro, 80GB Western Digital, Windows XP SP1, ATI Catalyst 3.5.

Test Software for both platforms will be:

SiSoft Sandra 2003 Memory
PC Mark 2002 Memory
PiFast
TMPGEnc AVI-to-MPG Encoding
Unreal Tournament 2003
Splinter Cell

Unfortunently, I do not have any 512MB/PC4000 sticks of competing products. We will be presenting benchmarks at 200FSB, 250FSB and the maximum OC on the P4C800-E, all in Dual Channel mode.

SiSoftware Sandra 2003 Memory - Pentium 4 @ 12x200

Although a synthetic benchmark, it's a popular one, freely available if you wish to make comparison benchmarks. We will be testing the memory speeds only.

PC Mark 2002 - Pentium 4 @ 12x200

For the two synthetic benchmarks, the tweaked timings show a slight improvement over the standard SPD. If the ram can handle it, there's no reason to settle for stock timings I always say.

PiFast - Pentium 4 @ 12x200

A good indicator of CPU/Motherboard performance is PiFast version 4.2, by Xavier Gourdon. We used a computation of 10000000 digits of Pi, Chudnovsky method, 1024 K FFT, and no disk memory. Note that lower scores are better, and times are in seconds.