AMD nForce2 memory timings explored

Memory by piotke @ 2004-01-04

A couple of days ago, I read on a Dutch forum a question concerning AMD timings. This week I saw almost the same question on our forums. It was a question about the fastest memory timings for an AMD nForce2 setup. Nobody could give a clear answer, so started to test the most common used timings... Here are the results you?ve always wanted to know!

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Short intro...

When you try overclocking and you post your results on a forum, you'll get a reaction like this:

- "What are your memory timings ?"
- "Well, says SPD in BIOS."
- "Set it to cas latency 2, and 2-2-5 !"

... 5 minutes later ...

- "My computer doesn't boot at these timings."
- "Bah, you got crap ram, go get your self some high performance sticks! With Winbond BH-5 memory chips!”

... You check the prices...

- "They're very expensive?!"

Seen this conversation before? Well, as a matter of fact, there are very few sticks that can do CL2 2-2-5 timings. Most ram even won't do "Ras To Cas Delay : 2" and "Ras Precharge : 2". Mostly it's the Ras to Cas that's holding you back, set it to 3, or higher, and problem solved. Most of these sticks have the famous Winbond 5ns chips. It really are wonderful chips, can't deny that. They go over 250MHz at these timings, at a nice voltage of 3.1 Vddr that is. You’ll rarely find sticks that match these high specifications.

Let's take TwinMos for example.
TwinMos once had a series of pc3200 memory with such chips, hard to find right now. Most of their memory modules you find currently have "50D" or "50B" chips. One letter difference = a whole other world of performance. The first are terrible, barely working at the rated 200MHz. The 50B chips on the other hand can do almost 225MHz on a healthy voltage of 2.85 Vddr. But what about their timings ? Well, I happen to have such sticks, on 225MHz they can run at CL2 2-4-11. Not bad, but no matter what I do, they won't boot at 2-2-5...

Recently, Winbond stopped producing the BH-5 chips, but because of the popularity they started to make them again, and now they stopped again, don't really know it for sure, but that's not the point.
The only memory modules that use such chips now are Mushkin Modules. “Yippiekayee” you would say? Not really, they sport a price tag almost the double of their TwinMos 50B brother...

So is it really worth spending that much money for these slightly different timings? I tested the most common memory timings and compared them against each other using a small range of benchmarks. Thank you RichBa5tard, who borrowed me his stick of memory.

As currently Nforce2 based mother boards are the most popular for AMD XP systems, I decided to use such a setup to test it. So the results could slightly differ on other chipset based boards.

Don't know what all these terms mean? Ras / Cas / Tras ? More and detailed information concerning this can be found here.

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