E8400 doa???

Do you have an extra MOBO to test it on or does your mobo have an error code?

no error code.. I put my old cpu back in and it worked fine.

Try a cmos clear yet?

Did you clear CMOS? Did you remember to plug in the GFX card and/or CPU power? What happens if you try to boot with just one stick of RAM, CPU and GFX? What happens if you try to boot with no RAM?

Update your BIOS maybe?

I have not done the CMOS or bios .Will be doing those things. (i have tried the cpu in one other motherboard but its a older asus motherboard as well)

The P5B which is a P965 chipset might require a BIOS update. I say might because not all manufacturers ever made a BIOS update to support 45nm CPUs.

No CPU will ever come DOA unless somehow exposed to EXTREME temperatures.

Well I just looked it up and Asus released a BIOS to support it.

this happen to me 6 months ago. but in my case it was the cpu. so try a different mobo and see if this happens

UPDATE.

installed new bios and the computer works fine now.

Cheers....