Agail: As I mentioned above, I think this board appreciates more NB voltage when using the newer 45nm CPUs. My NB is only air cooled but it seems to like having the NB set to 1.65 volts in the bios. On the previous page I posted some bios voltage settings that are working good for my E8400 - C0.

http://www.xtremesystems.org/forums/...postcount=4925

I think the facts of life are that this board is a couple of years old now and it is not really optimized for some of the newer memory. Some new sticks that can run DDR2-1200 speeds on a newer board with a newer chipset probably won't be able to run that same speed on a P5B Deluxe. Asus makes a little bit of progress with each bios release but it just isn't that high a priority for them.

When you say that you can't get them to run at the rated speed does that mean they aren't Prime stable or you can't even boot up?

I was having some boot up issues before (it would hang) but I was running some mismatched sticks. One was a Ballistix 1GB and the other was a Team. With the extra voltage and some new OCZ DDR2-9200 Reapers it's been trouble free lately.

It's also possible that your CPU might need a little more voltage now. After the initial burn in some 45nm CPUs need a little more voltage to run the same overclock.