I am trying to upgrade an Acer Aspire T690 that has a bizarre quirk. Once it is running it will work with any suitable RAM that is installed, as might be expected, but it will only start if one of the memory slots contains a 512 mb stick of the original RAM that came with the computer. This is DDR2 667mhz, also variously known as PC2-4300, PC2-4200, DDR2-533.

 

I am looking for RAM of any size 2gb or less and frequency 667mhz or less in an attempt to find another module that this computer can start from. I need a backup in case the one and only module that currently works dies at some point. I can't find any specs to differentiate the one that works from the ones that don't, so I'm just trying to collect random modules in the hope I will get lucky. If you have any old 256mb or 512mb sticks that are not doing anything, I would be grateful to have them. I am also happy to pay for postage plus something more for larger modules.