I have 2 pairs of ram sticks, one pair is CAS 2 DDR400 and one is CAS 2.5 DDR400. When I use them all at once, I have to set the memory frequency to 100mhz (so it's ddr200) otherwise I get an error saying "cpu is now in safe mode, please resetting cpu frequency in bios or press f1 to continue." I also remembered to set the thing to 2t when using all 4 at once, but it doesn't help. Anyone know why? Specs Athlon64 3500+ 7900GT Chaintech VNF4 Ultra 4x512 ddr400 Oh and is it even worth it to put the 2 extra slower sticks in? When I do, my tras speed or whatever goes to 15T instead of the 8T with the faster pair, and I get to use 1T setting if I just use 2 sticks instead of four.