Howdy,
There are a few things: 1.) make sure his mobo version is fully compatible with the 45nm E8500 CPU, some motherboards will only handle the new 45nm CPU's after a flash bios upgrade. This is a pain as it involves getting an older 65nm CPU, booting, installing windows, upgrade flash, etc
2.) The other thing is that the E8500 CPU running at FSB speed of 1333 has a base frequency of 333, where as the DDR2 6400 memory (DDR2 800mhz) I believe requires a base frequency of 400mhz... or is it 200... memory timings confuse me.