Memory problem?

[NotAllThere]

I've bought 1GB extra memory for my daughter's PC. ( Self build, AMD Athlon XP 2000 +, XP SP3 ). It already had 2 0.5GB memory modules installed. ( PC2700 CL2.5). I put the 1GB module into the third slot. BIOS memory checks ok. But various BSOD, cycling, safe mode sometimes comes up, but doesn't work properly - shaky mouse pointer.

If I take the module out, all is ok. If I put the module into slot 1, and leave slot 3 free, all is ok. If I put 1GB into slot 1, and 0.5GB into slot 3, it also works fine.

So the memory modules are ok and the slots are ok. But I can't put 2GB in? Any ideas why?

edit: I suspect that the motherboard may not be able to handle 2GB.

edit again: no - it's a asustek a7v8x-x which can support 3GB

edit again having read the manual: Max. 3 GB unbuffered PC2100 / PC1600 non-ECC SDRAM Memory (PC3200 Max. to 2 banks only / PC2700 Max to 4 banks only) 512MB is 2 banks, 1 GB is 2 banks. So using all three slots gives... 6 banks and so it doesn't work.

ta

[doodab]

It might be that the memory controller has other limitations re: # of banks or mixing module sizes. Google turns this up:

ASUSTeK Computer Inc. -Support- FAQ FAQ 3 DDR333 memory cause system unstable on A7V8X-X

[doodab]

You should be able to use 2 x 1GB though?