Ran asus P5Q motherboard

If its DDR2 800 memory than it runs at 400Mhz, not 800

my mobo can go up to 1066 what size should i get if i want 800mhz or1066?

Sorry but i dont really get what youre asking

DDR2 800 runs at 400MHz

DDR2 1066 runs at 533MHz

Its more about what memory modules you have, not what speed your mobo supports

thanx I have been reading up on ddr2 ram and I now know what you are saying
the asus mb can run pc1066 so thats what Im going to get. again thanx for your help. Ive read some of your other blogs too just wish I knew this stufffff sooner

No worries