You got your numbers a bit scrambled there, incubus. He currently has 256 Meg, rated at CAS2. If he's got stability issues (not stemming from the OS), then he's most likely running at CAS2, and the RAM he has is on the outskirts of CAS2 rating. If the new stuff is also CAS2, there theoretically shouldn't be a problem. However, the CAS2 rating has some leeway in it, and the new stuff could be worse... especially if he is overclocking to begin with.My recommendation, put the new stuff (128Meg worth) in the system, then run into the BIOS and switch your Mem to CAS3. It's not the worst thing in the world. I have to run mine at CAS3 since I'm overclocking it so much (133 @ 155). Having 384 worth of mem will outweigh the access time issue. Plus, if you have a good amount of cache, then you don't have to worry about that latency much of the time anyways.