Motherboards have a limit on how much memory can be installed in their sockets. Just because you have an available empty socket doesn't mean you can plunk another memory module in it. You did not mention the brand, model of your PC so we can't answer whether your system supports 2 GB of RAM or not. I would bet it does as 2 GB isn't that much memory, but you should look in your user manual for the PC or check the manufacturer's website to see just how much memory your particular system supports. -- qfreed "hash" wrote: > hello > > i've vista ultimate and 1gb ram. before i had 512 mb ram. since the > upgrade to 1gb i've noticed an improvement in my pc's performance. it > responds very quiclky to most clicks. > > what i'd like to know is whether upgrading to 2gb ram will make it even > better or faster ? please advise if my pc would be compatible to 2 gb or > would i notice any difference in speed from 1gb to 2gb. i've 2.8 ghz > pentium 4 pc. > > the original ram's spec is 184-pin pc2100 (266 mhz) dimm. can i get 2 x 1gb > ram module with the spec. mentioned to go in the two dimm slots ? do > 184-pin pc2100 ram come higher in speed than 266mhz. ? please advise. > thank you. > > regards > hash > >