Hi. I am trying to add more ram to my system. I currently have a PC2100 512mb (266mhz) installed in DIMM1. I just bought another PC2100 512mb (266mhz) to add. The problem is that when I insert the new memory into the DIMM2 slot, the computer won’t load up. Not even to the Bios. I know each one works because if I load up individually on DIMM1 slot, my comp works fine. Is there some sort of configuration on bios I must do before I can add more ram or maybe DIMM2 slot is damaged and cannot read?

What motherboard have you got? It sounds as though you've got a dual channel option, though to use it you have to use pairs in certain slots - alternative configurations may not work which would explain your problems.

Consult your manual and see what it says - My motherboard, for instance, has two banks of two DIMM slots - one bank can be used with any combination of RAM modules, the other is dual channel and therefore requires two identical RAM modules to function properly (possibly at all).

Have a look at the manual or find out what board you've got and we can probably give you more information. There may also be a jumper on the board, though without knowing more I can't really tell you.

One thing you could try is to use slots 3 and 4 (If you have that many) - Slots 1 and 2 on my board are the dual channel bank which I don't use.

ok there's only 2 slots for the memory. My motherboard is Machspeed 865PEDAP.. i believe... running 3.0ghz P4 HT