I have recently built up my first PC however when I switch on the power there is no signal going through to the monitor and there is no beep everthing else switches on ie the fans, hdd etc could this be as the motherboard has an 8pin power socket for the CPU and my PSU has only a 4 pin power lead to plug in to it?? If it helps at all here is a list of the components in my PC. If it is my PSU has anybody got any suggestions for a new PSU that will supply enough power to the below setup but with another Geforce 8800GT as I will be adding a second one shortly??

Intel Core2 Quad Q6600
XFX Nvidia 680I SLI Motherboard
BFG Nvidia Geforce 8800 GT OC
Corsair XMS2 DDR2 2GB RAM
Samsung 250GB SATA HDD
Pioneer DVD-RW
EZCool 550W PSU
Antec 900 Pro Gaming Case

Many Thanks

If the CPU power connector on the motherboard is a eight pin and you aren't using a eight pin connector then yes this could be a problem. You might google to find an adaptor.

Ive just installed my new power supply and there is still no post from the PC what else could be causing the problem?? please anybody help cuz i feel like throwin it out the window!!1

just something to try: a full CMOS reset and boot with just 1 stick of RAM (I'm no expert, but this could be more useful than throwing it out the window). Otherwise, do you have another PSU and/or CPU you could try?

This will probably sound dumb but how do you reset rhe CMOS?? (im pretty new to the PC building thing):D

Firstly, with a new PSU and no post, personally I'd look at sending back the motherboard for a replacement. If you want to try a CMOS reset it's not that difficult (should be in your manual).

You just unplug your power cable from the computer, then move the jumper one notch. It's item 17 in this picture [img]http://i107.imagethrust.com/i/683274/mobo.jpg[/img]

There's 3 pins, with the jumper joining 2 of them. Just move it one space to join a different 2, then in a few seconds move it back. Power up and see how you go.

If you do send back the motherboard you really shouldn't bother telling them that as you were short of a power supply you decided to try one without the appropriate connections. Who knows what damage may have been caused by that poorly thought out manoevre.
In the event that you may have driven too high a voltage onto any of your voltage rails eg. 12V onto a 5V or GND rail then perhaps the exit out the window is not such a bad idea as it may fly better than it will ever process.