Memtest errors. What do they mean?

I've just installed 2 512MB sticks of DDR RAM (Crucial Ballistix PC4000) to go with the 2 512MB sticks already in the machine. Games that ran fine before the upgrade now crash quite quickly, so obviously something has gone wrong with the RAM.

I ran a copy of Memtest i had on a bootable CD (v3.2). After 1:14 the tests had ran twice, and I had 16 errors on test 5 (8 on the first test, 8 on the second), and 2 on test 7 (both of these on the first test).

I wrote down some of the numbers in the error details, and I can provide them if needed, but I was hoping that someone could tell me what these errors actually mean, and if it can diagnose exactly where the fault lies.

I intend to test each stick individually soon.

(P.S. All sticks are running at 400)

As I'm sure you've figured out it means that there is some sort of memory corruption, i.e., what you write to memory is not neccesarily what you get. This can make any program crash since a if a pointer to an address in memory is changed a program will try to access an illegal bit of memory with unknown contents, need I explain any more. To solve the issue a few questions:

Any OCing?
Any thermal issues you've had with the computer?
Have you reseated the memory and visually inspected contacts?
Can you RMA the stick?

I've always binned ram that didnt work at its rated speed.
If its new send it back.

Never had any thermal issues with the PC. Temps are still fine now.
No OCing. I tried OC a graphics card about 5 years ago. It went wrong. OCing is banned from my PC :p .

As I said, I'll be pulling the sticks out and trialling them individually, but I was hoping that all these numbers from the errors (Failing Address, Good, Bad, Err-Bits) might yield some clues as to what exactly is to blame.

What is slightly bizzare is before the new sticks went in, the mem was running fine at DDR400 speeds. When the new sticks went in, the BIOS automatically went to 333. These new sticks are rated at 500, which is confirmed by CPU-Z, so I can't figure that out. I manually set them to 400 in the BIOS.

I'd do a few more quick test, but if it doesn't work you paid to buy them to have them work not to debug them, so....

Quote:

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Originally Posted by Trig

If its new send it back.

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The drop to 333 is normal when using 4 sticks on an S939 set-up. It's a limitation of the CPU.

Also, if the 2 new sticks are different from the old 2, then it could be incompatability that's causing the problem.

Only way to be sure is to test all 4 sticks individually. If all pass, try the 2 new ones in dual channel mode. If they are still OK, you could buy another 2 of these and sell the old 2.

A lot of ifs there, though.

If you're setting the timings manually make sure the command rate is 2T.

Well, I've tested the 2 new ones individually, and together as a pair in dual channel, and they work fine.

All sticks work fine together at 333. I wasn't aware that there was a speed limit on 4 sticks. That kinda leaves me running at 333 if the errors show up when I force it to 400.

Am I going to take much of a performance hit from dropping to 333 from 400?

Didn't read careful enough. Yes 4 sticks can be a problem due to the unpleasant nature of capacitance and refelection of electrical signals (due to termination, or the lack thereof). Start by taking charlski's advice. If that doesn't work try things like swithching the positions of the pairs, you never know. As for the preformace hit you could benchmark you favorite games with 2X512 @400 and 4X512 @333 and see which works better. If the memory is not helping you return it while you still can.