I have a HP XT 938 with a Athlon 1300Mhz processor and the RAM is 256 MB. I have a PC100 512 MB card from another HP computer could I run this in my XT 938. If yes can I leave one of the 128 MB cards in place (1-128 slot 1, 1-512 slot 2) I think the mem cards in place are PC 133's. Thanks, Bruce
If both the old and new memory modules are DDR, not DDR2, then you can certainly try the big one and see if it works. And maybe try the 512 by itself also - if it works only by itself, you've still doubled your RAM. As long as the module fits in properly - the notches are the same when you compare the modules to each other, won't harm to try it. Worst case the computer ignore it or fail to boot.