DDR2 400 memory with with a DDR2 800 board?

[opentoe]

I have an Asus P5AD2 mainboard with DDR2 400 speed memory installed. All the new boards of course start with 800. Will my 400 speed memory even work in one of these new boards?

I currently have a P4 3.4Ghz machine with 2gig memory and want to upgrade to a dual/duo core processor and mainboard....but not sure if I need to replace the memory or not. If I do, I'll probably just stick with what I have, since the memory would be the most cost in this upgrade.

Also, can anyone recommend a stable good Dual Pentium board that's not $250? I don't need three NICs or every option available. Just HD audio, 1gb NIC and the basics really.

Thanks!

 

[yas]

For a c2d processor u definately need DDR2 memory although im not sure if DDR2 dimm slots are backawrds compatible and work with DDR.

 

[Mex]

I'm confused? Do you have DDR 400 or DDR2 400?

If it's DDR 400, you can't reuse it, as it won't fit in a DDR2 slot. Even if it could fit, the voltage that DDR needs would probably short out the slots.

If it's DDR2 400, then you can reuse it in a new board. The DDR2 800 listed with the board indicates the maximum official speed it can handle (I say official because DDR2 1066 is not an official JEDEC standard). However, you may want to consider bumping it up regardless. If you're considering a Core 2 Duo, at least bump your memory up to DDR2 533 so it isn't bottlenecking the processor.