Hi! Short answer: In reality, without knowing the exact motherboard and rev, and possible processor (AMDs have DRAM controller internal), no one can say with 100% certainty! :) Sorry, anyone that tells you otherwise likely isn't a hardware engineer (like me), has never done high-speed DRAM design (like me), has never done a high-speed signal integrity intensive design (like me), and/or has never used $$$$ signal integrity tools (like me). In reality, every DRAM module model number is different! That includes speed and module Rev number. All motherboards list tested/approved DRAM modules, the capacities, the speed, the module part number. In reality, without that info, it is a total CR*P SHOOT!! Some capacities may and may not work. Some speeds may and may not work. And, if it's an older motherboard, good luck finding those specific part numbers! There are many real life issues with DRAM modules. They all differ in capacitance, trace length, trace matching, impedance differences (trace to trace), etc. And, every DRAM has different (but "very close") specs - even for the same speed/size/etc. There are hold time, setup time, capacitance, tolerance of termination, etc issues. In general, you can likely put in 1GB DRAM module in each. As long as they are the same speed grade as your current 512MB module(s). Your best bet would be to go with name brand modules that support faster access times. BUT, there is a "decent" chance that you may have to tweak your BIOS settings to lower the DRAM access speed, and/or lengthen the accesses. Consider it like speeding on the highway during a holiday. You know there are speed traps. But, still, "most/many" people can speed and not get caught. Same with doing a DRAM upgrade without going by the Manufacture's manual. BTW: I very very strongly suggest that you do a disk image before you try out a DRAM upgrade. However again, many people speed during the holidays, they don't have radar detectors, and they don't get tickets. Just because something is foolish, doesn't mean that people don't do it, and not get screwed. For me, I avoid doing foolish things if I know they are foolish beforehand. Wish I could be of more help. Oh well. At least I can say "it won't be a massive loss of money if it doesn't work". :) (And, of course, you first did a disk image.) Good Luck! _____ Joe Principal Hardware/Software Engineer over a dozen years. Hardware/So