I've recently purchased two sticks of PNY 1GB DDR PC3200 RAM. I did the system scan at crucial.com and thats what it advised as my maximum. I have an old Compaq Presario SQSXE1 which previously had 2 x 256 PC2100 running fine. I installed the ram one at a time. Put in 1 gig, works fine. Put in the 2nd stick, Compaq screen comes on, the memory check in top right-hand corner goes up to 2gig, but then goes to a black screen and windows does not load. I have tested both sticks individually in both slots, works every which way. I have put both sticks in at the same time and switched them, same results. I'm not sure what information you need from me but I'll be happy to try and get it if I can. My knowledge of computers is unfortunately minuscule. Thanks for any help you may be able to provide.