The main reason why I tried to upgrade with the dimm module was because dimm is so much cheaper (in this case free -it was given to me). Doug, I tried your sugggestion about not mixing, but when I removed the simm modules the computer wouldn't boot at all, just got beeps. The simms would work alone but then I would only have 16mb (4x4mb). But the whole exercise hasn't been a waste of time. I've learned a lot (and I'm sure other newbies following this thread too) about latency and CAS from to Bill and about different types of Ram from other people here. Thanks. Julie _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp Visit our website regularly for FAQs, articles, how-to's, tech tips and much more http://freepctech.com