Sudden Memory Trouble - Bit Perplexed Could Use a Helping Hand.

[Mencius]

Hi Folks,

My apologies for posting a few very basic questions here but while my technical knowledge is semi-competent (emphasising the semi) the situation I find myself in at the moment is taxing me quite a lot. I'm using an AMD 64 3400+ on an Albatron K8X800 Pro II (v.2.0) motherboard.

I've been running this system configuration, and it's been quite stable, for 1-2 years now. Last night I encountered an error which lead me to believe I may have a failing RAM stick. The screen blanked out and back on showing visual anomalies (green and purple distorted colours) and then the system hard rebooted. Needless to say this caused a pretty deep sinking feeling.

My motherboard's helpful diagnostic PC Speaker voice confirmed my fears "your memory may have a problem". Now I skimped on memory when I built this machine, I'm running with two PC3200 512MB sticks, they've got mismatched timigs: 2.5-4-4-8 and 3-3-3-8. However they've been running OK for nigh on two years now. I've left BIOS memory settings basically untweaked and set to auto.

Here's the root of my problem: the system is stable with either stick in any slot but not with both. I've run memtest on both sticks individually and on them combined. Individually both sticks pass memtest (though I haven't run exhaustively long tests yet) but together they fail in the random number phase of testing (at about 18 minutes in). The system is also unstable in any memory intensive application under windows with both sticks in.

So my question: what could cause errors with both sticks together but cause them to pass testing individually? Could it be to do with the timings? Or is this perhaps the sign of motherboard failure? What would be some very "safe" timings for me to manually set in BIOS to see if I could make these modules pass testing?

Once again sorry for the basic questions, I would really greatly appreciate any help anyone might be able to offer me. I'm getting rather frustrated at this stage.

[(cf)Eclipse]

sadly this is one of those areas where you have to guess and check to see if an error is really an error. at first glace, i want to say that the two memory sticks do not play nice together... but why would it work fine up until now? have you tried bumping up memory voltage to 2.7v in the bios? if that helps, it must be that the memory is slowly failing

if it doesn't help... :confused: for now

[Mencius]

Thanks very much for the reply!

Fortunately I have made some testing progress. When scaled back to 333Mhz the memory will pass memtest and seems to run fine with both sticks.

So could the problem be that the timings configured by the BIOS at 400Mhz are causing conflicts between the two sticks?

Here is the SPD data:

Stick 1
166Mhz: 2-4-4-7
200Mz: 2.5-4-4-8

Stick 2
166Mhz: 2.5-3-3-7
200Mhz: 3-3-3-8

Now, from memory, when set to 400Mhz I believe the BIOS was selecting 2.5-4-4-7. I don't understand the details of timings well enough to know if this is an incompatible timing. However, it clearly seems that it has been causing trouble. It is certainly strange that the PC has been functioning until now. Perhaps I have just been lucky and this problem was always there and just waiting to cause an error.

What timings should I select for compatibility between these modules at 400Mhz? Would 3-4-4-8 be the correct timing?

[(cf)Eclipse]

it seems quite likely. give 3-4-4-8 a try and see what happens. worse comes to worse, it's simply not stable like the other settings :p

[Mencius]

Hmmm passed one pass of memtest at 3-4-4-8 at 400Mhz but sadly wasn't stable in Windows after a little while. I guess I'll just keep running at 333Mhz for now. Any other timings I should try?

[Mencius]

Some further progress: It is stable at 400Mhz at 2.5-4-4-8 at 2T but not at 1T. However at 2.5-4-4-7 at 333Mhz it is stable at 1T.

I assume I'm better off using 2T at 400Mhz?

[(cf)Eclipse]

i would assume so, but you can try both and run some programs that can give you a performance score (like game benches, 3dmark, cuperPI, etc) and see which is better :D

[Mencius]

Yep I think I'll stick at 2T 400Mhz. Thankyou very much once again for your help. Everything seems to be running a lot better now and is more responsive (which would make sense if I've had misconfigured settings for all this time).