PC Memory.

[Joe]

Col's current PC Thread is too important to take down side-roads so I thought I'd better start a new one.

This is what's puzzling me:-

My computer only had 500M ram Joe so I bought 1G through eBay and added it hence the 1.5G.

I'd always been lead to believe that pairs of RAM modules had to be the same size, ie two 512MB or two 1GB.

A long time ago I tried installing a 512MB one along with a 256MB one and the PC refused to boot.

I did the exact same up-grade as Col but removed the 512MB one. If it will work along side the 1GB one I may as well put it back. I'm loathe to just try it as access to the slots isn't very easy on this machine.

- Joe

[Nick]

Depends on the Chipset. Some memory controllers require matched pairs, some don't, but for performance reasons you normally use matched pairs with identical capacity and timing. If the chipset supports dual channel & you install matched pairs (in the correct sockets), then the controller will overlap memory access to gain speed (x2 at best, i.e. memory bandwidth is doubled). This is why a lot of memory is sold in pairs - sometimes its better to buy 2 x 2Gb DIMMs rather than 1 x 4Gb etc. When I say "pairs", I mean exactly identical in size, model, bus speed, timing etc. Just using, say, any 2 1Gb DIMMs and hoping will almost certainly not do the trick.

MBs that support this (pretty much all modern ones) will have an even number of memory sockets and often the sockets will be colour-coded in pairs.

Memory is cheap. Just do it!

HTH

[Joe]

Mine's a 2002-vintage HP so probably won't. I may give it a go if I have the cover off for any other reason.

Thanks

Joe