wrote:
Just bought a GByte GA-P41-ES3G and fitted CPU Intel 430 LGA 775.
CPU fan only spins a few seconds then stops. Nothing on the screen, no
bios display. The PSU is a bog-standard 20 pin plus the extra 4 pin
plug nr the CPU. Should I invest in a 24-pin PSU, would it make any
difference? Do people use a 24 pin PSU AND the 4 pin 12V plug?

Make sure, that the four pin you're plugging into the ATX12V
power plug on the motherboard, has two yellow wires and
two black wires. The two yellow wires are +12V and that
is used by Vcore to power the processor.

There is another four pin thing you can plug in by accident,
and it has four wires of different colors. You don't want
that one.

The 20 pin should work fine, to power a 24 pin equipped motherboard.
The latch on the connector, goes on the same side as the latch
fitting on the motherboard. Pin 1 of the connector, goes to
pin 1 on the motherboard. The "shapes" of the nylon shell, help
guide a correct fitting.

(Using a 20 pin connector, on a 24 pin motherboard)

http://www.playtool.com/pages/psuconnectors/20in24.jpg

(Two yellow and two black wires...)

http://www.playtool.com/pages/psuconnectors/12v4pin.jpg

(Fitting a four pin ATX12V, on an 2x4 equipped motherboard.
Probably not an issue for your motherboard, but included for
future reference. The latches are to be lined up.)

http://www.playtool.com/pages/psuconnectors/4pinin8.jpg

It sounds to me, like the power supply is being overloaded,
by something you're doing to it. That's why I'm suggesting
verifying the connections. Maybe it's not your fault,
and it is a bad, brand new power supply. But it doesn't
hurt to check the wiring.

Paul