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Corsair XMS 6400 Problem

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bobad

Member
Joined
Apr 19, 2004
Location
Louisiana
For ~2 years I have been using a 2x1 gig kit of Corsair XMS 6400 RAM rated at 5-5-5-18-22 at 400mhz.

I ran it on a P5B, and it ran fine and overclocked well unless I tried to manually set the timings. If I set it to manual, it would fail, whether I relaxed or boosted the timings. I figured it was an incompatibility betwixt the Corsair and the P5B.

Well,,, I now have a Gigabyte UD3R (see sig) and it does the same thing! Runs great, passes Memtest and everything, but won't allow me to manually change the timings. I may want to kick my E8400 up a bit, and I wanted to be able to loosen the timings if necessary.

Can anyone tell me what may be going on with that RAM? Does that sound weird, or is it common?

Thanks,,,
 
More info

What kind of RAM is this? DDR2?

Also, can you post your timings? And have you tried setting the command rate to 2T (or 2N)?

Have you tried setting all timing numbers to their MAXIMUM possible values? You might want to do that and experiment by lowering them a bit at a time until some stress test fails. On Linux, I use mprime, which is similar to Prime95 under Windows. I find mprime to be a bit more aggressive.

Also, how about underclocking?

Basically, I'm suggesting debugging steps. What timing numbers do you expect? Compare those to what you can actually get.

One thing I think I have noticed is that when I first got OC RAMs several years ago, the SPD contained JEDEC timing numbers. In other words, your 5-5-5 might actually have 6-6-6 in the SPD. You may not have been getting the speed you thought you paid for. However, I have found that SOME recent DDR3 performance RAMs actually program the SPD with the more aggressive timing numbers.

And sadly, I have not had always had good experience getting performance memories to run at advertised speeds. I think some of the performance RAM vendors WAY over charge for memories that have been speed-binned VERY minimally. They haven't been put though enough testing to be, in my opinion, properly certified to run at the advertised speeds. This is why I buy regular RAMs and speed test them myself. To begin with, I only paid for standard (JEDEC timing) memories, and I might get lucky. I have the best luck with Crucial because it appears they are ULTRA conservative in their speed binning.

One other thing: Silicon ages. I'm not totally familiar with all the ways in which that happens, but one of the major ones is metal migration, in the interconnects between transistors. Recent DDR3 memories probably have transistors that are 45nm or smaller, and at that size, aging effects are very significant. OC'ing accelerates aging, especially when you have to increase the voltage. When circuits age, you have to underclock them to get them to run reliably (or keep raising the voltage until it fries).
 
What kind of RAM is this? DDR2?

Have you tried setting all timing numbers to their MAXIMUM possible values? You might want to do that and experiment by lowering them a bit at a time until some stress test fails.

Yes, the P5B and UD3R are both DDR2 boards.

Like I said, it fails to boot when set to manual no matter what the settings.

When set to auto, it boots fine, and selects the proper SPD, which is 5-5-5-18-22.

Has anyone experienced that, or is it faulty RAM perhaps? (although it passes MEMTest 86)

Thanks,,,
 
What kind of RAM is this? DDR2?

One other thing: Silicon ages. I'm not totally familiar with all the ways in which that happens, but one of the major ones is metal migration, in the interconnects between transistors. Recent DDR3 memories probably have transistors that are 45nm or smaller, and at that size, aging effects are very significant. OC'ing accelerates aging, especially when you have to increase the voltage. When circuits age, you have to underclock them to get them to run reliably (or keep raising the voltage until it fries).

This cracks me up....These two statement are actually in the same post?
 
I cant set my mobo to 5-5-5-18, it maxes out at 15. but using Auto it set it to 18, these Corsairs are kinda touchy, I feel if i set it to 5-5-5-15, they'll die. Anyway, did you try bumping up the RAM voltage a notch? it's worth a shot.
 
My guess is that the cause of the problem is that the BIOS won't let you manually set that 18. 15's too low. You can try increasing the voltage. But the ideal thing would be to have more control over the timing numbers.

Have you verified that your BIOS is up to date? They may have a newer version that has more range on those numbers. Updating BIOS can be a real pain, though.
 
:D

This is getting hilarious! I busted out laughing so hard I almost cracked a rib!

A condensed version of the conversations go like this:

Dumb: "My computer won't boot unless my RAM timings are set to automatic."

Dumber: "Try manually setting the RAM to looser timings". :clap:


Sorry, not trying to be ungracious or disrespectful, but it made me laugh.

My question is, has anyone ran across this problem, and what is the cause?

Another funny thing is, on Auto and 5-5-5-18-22 (automatically chosen through SPD), my E8400 overclocks beautifully to 4005mhz.

I'm using the fairly new F5 Bios, and many of the guys prefer it to F6 and F7. I tried bumping my RAM voltage.

Thanks again,,,
 
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