I have a users pc that died I tried changing out the psu still didnt work, well it just made a humming noise.
I have now changed out the motherboard and cpu, which gave me power back, fans working cd roms ejecting but hard drive no activity also no display. I then put in a new graphics card new hard drive but still the same adn I have tried it with only the har drive attached but still the same.
Im guessing the replacement motherboard and or processor has gone.
Any ideas anyone.
Cheers
Dave

try it without hard drive attd. No drives at all. A working PC will still fire up and give you image on screen and access bios/setup with no drives att'd.
Do it without the motherboard in the case.
lay motherboard on soft surface so as not to damage back of it. On the motherboard you should have
1) cpu and heatsink
2) ram
3) graphics card
connect psu, keyboard and monitor.
use a screwdriver to momentarily connect the two pins that are for the power button and if all is well it will start up and show image in screen.

Thanks for the reply, I have just tried that and only the psu fan and heatsink fan comes on.
Do you think thats the cpu ?

Thanks
Dave

Try that CPU in a known good motherboard or Try a known good CPU in that motherboard. Often when a powersupply has failed a number of other components have gone out in cascade. I had a system fail and the only bits that were recoverable were ram and drives. The CPU, Motherboard, powersupply, graphics card, PCI modem and network cards were all dead.

I used to have a signature but it disappeared and I just couldn't be bothered writing another so please feel free to ingore this.