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Review: Corsair XMS3500 C2 Memory

by Tarinder Sandhu on 7 November 2002, 00:00

Tags: Corsair

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Specifications and analysis

The test module, a 512MB single, double-sided DIMM in this case, arrives with Corsair's trademark XMS black heatspreader and retention clip. The code on the label informs us that it's the very latest module with XMS3502 in its title. All's good so far. Let's now investigate the official specifications.


  • 256MB and 512MB modules available

  • Implemented using 64M x 8M DDR SDRAMs with 5.0ns access time

  • 100% tested at 217MHz (DDR434)

  • Integrated aluminium heat spreader for improved thermal performance

  • Lifetime Corsair warranty

  • Six-layer construction

  • Each module is tested in only an ABIT KD7 (KT400) motherboard with a CPU at 145FSB and the 2:3 FSB:Memory ratio used (145 x 1.5x = 217)

  • Latency: 2-8-4-4-1T @ 2.5 - 2.55v

  • SPD programmed at proposed JEDEC values of PC2700 (PC3500 not defined by JEDEC yet)

The specifications leave me with a mixed feeling. The modules are only tested on an AMD KT400 platform using a 2:3 CPU:Mem ratio. What that means is that at 133FSB (CPU's default) the memory is running at 200MHz (DDR400). Raising the CPU's FSB to 145MHz allows the memory to run at the stated 217MHz. I've mentioned that the Athlon XP runs best with synchronous memory. Why is that ?. The Athlon at 133FSB can make use of 2.13GB/s of memory bandwidth (PC2100) due to its double-pumped FSB. Running system memory much beyond the FSB's speed pays little dividends as we have all the bandwidth we can use. At 145FSB, running system memory at 217MHz is absolutely pointless because the CPU cannot use it. You'd be just as well off running memory at 166MHz.

Secondly, why weren't the modules ratified on a platform that can readily make use of PC3500 memory ?. The P4 with its quad-pumped FSB can. The SiS648 chipset has the appropriate dividers to allow you to run asynchronously, and we've seen just how well performance scales with greater bandwidth.

I'm going to be critical and state that Corsair have ratified this memory to run at 217MHz and CL2 on a platform that gives them the easiest possible timings. Timings of 2-8-4-4 are not available on any major Intel motherboard; they're simply too lax. The most relaxed timings on a P4-based motherboard (excluding the CAS rating) are 7-3-3.

I have a feeling that Corsair, quite understandably, felt that they could not validate their modules to 217MHz with 2-7-3-3 timings at default voltages; that's why we see no P4 motherboard validation in their specifications. It seems as if Corsair have tried their utmost to keep a CAS latency of 2 clocks and still validate the modules at 217MHz. The only way to do that was use a motherboard that gave you the option of running extremely weak timings alongside CL2.

So if you're buying this memory on the premise that you will run it asynchronously on a P4 platform at 217MHz and CL2, you'd best think again. This memory currently is not rated at 217MHz CL2 (default voltage) on any P4 platform, and only is on a selected AMD motherboard with poor associated timings.