RAM or Motherboard posessed of demons?

[fluoextinchcl]

I have an ECS K7VZA motherboard, an Athlon 2200 XP cpu (1.8GHz), and several pieces of Azen (cheap but not crap) brand pc133 RAM. Recently the computer has been locking up, refusing to boot WindowsXP Pro SP-1, spontaneously rebooting, and (my personal favourite) powering off all by itself. I concluded that demons had infested it somehow.

It’s not a cooling issue, nothing is overclocked, there is Artic Silver under the heatsinks, and the myriad fans are spinning. Motherboard Monitor 5 says everything is well below safe temperatures.

Suspecting bad ram, I checked using a little program called memtest86 v3.0 www.memtest86.com. I have 2 pieces of 256MB and 2 pieces of 128MB. Up until now I had been running 2x256 + 1x128 for a total of 640 with no trouble. I have another piece of 128mb that was mistakenly purchased and rarely used sitting on the desk in it’s original packaging as a spare.

I have spent a long time testing all possible combinations:

• Every stick of ram tests with no errors when installed all by itself.
• It tests with no errors in all three of the motherboard’s DIMM slots.
• When I add a second or third piece, in any combination of size and motherboard slots, memtest86 finds between 100 and 100000 errors, usually on Test 5.

Test 5 [Block move, 64 moves, cached]

This test stresses memory by using block move (movsl) instructions and is based on Robert Redelmeier’s burnBX test. Memory is initialized with shifting patterns that are inverted every 8 bytes. Then 4mb blocks of memory are moved around using the movsl instruction. After the moves are completed the data patterns are checked. Because the data is checked only after the memory moves are completed it is not possible to know where the error occurred. The addresses reported are only for where the bad pattern was found. Since the moves are constrained to a 8mb segment of memory the failing address will always be less than 8mb away from the reported address. Errors from this test are not used to calculate BadRAM patterns.

I have been able to get the system to test error free and run Windows without demon induced crashing or reboots by changing the motherboard jumpers that control Front Side Bus clock down from 133 to 100. This makes my CPU run at 1.3GHz.

I’ve never seen this kind of issue where RAM works when installed single, but not in pairs or triples. I do not know if there is tag or cache ram on this type of motherboard? I need to know what has to be replaced. Do I have bad RAM? Or is it a failing motherboard?

[gotpasswords]

If you have to underclock like that, I’m guessing your RAM’s just not up to the challenge.

This may sound silly, but have you confirmed that you have the right flavor RAM for this mobo? Have you confirmed with the mobo’s documentation that you’re putting RAM in the right order? IE: some boards may want the largest stick in the first slot, or they may need identical sizes in all slots, etc.