I have two computers that both use PC2100 266mhz.DDR ram.One is an HP TC2120 server and the other is a PC chips DDR266 motherboard.The DIMMS both have the same # of pins(184) and fit in each others slots but will not work if interchanged.In doing some research I have found server memory is different from PC memory. My question is how in the world do you know which is which when buying more ram for them as they both have the same #(PC2100 266mhz DDR)?

A pretty good discussion about the subject is on this thread.

Also, most memory manufacturer's web sites have decision trees that guide you to what RAM works in your specific system or motherboard.

Of course, there is also the users manual for each, as well as information on the server or motherboard manufacturer's website.

Ok I read the thread and I get it now.. Perhaps the manufacturers should not place the letters "P.C." in front of server memory. Maybe it should be "SVR2100 DDR" or something along those lines for us wannabe computer builders.I picked up this H.P.TC2120 server for nothing not knowing it was different from a regular PC but it only has 128 MB RAM. I have now ordered 4 256mb ECC reg.for it. and by the way I wiped the redhat server software off of it and installed windows XP home with no problems and it seems (Other than memory issue) that is going to work as a home computer just fine. It has 2.0 ghz celeron in it and I had to install a sound card...and oh yeah it is in fact kinda big LOL. Thanks for your threads and your time to answer my dummy questions.