New system wont boot

[abaddon]

I have just installed the motherboard and everything, and gone to turn it on and it doesn't do anything.

I am using my Targus TG480-U01 power supply and have plugged in both the atx power connector and the 8-pin 12V connector but when I turn the power on, nothing happens.

The mobo is the Asus P7P55D.

Any ideas? Pretty annoyed as I've just spent past hour and a half putting it together.

EDIT: False alarm gladly. Changed the power lead and it now boots. Must have been a dead power lead.

[abaddon]

Annoyingly, I now am experiencing intermitant VGA issues. Sometimes the computer will boot fine and display the BIOS etc, but then when it restarts it developes a fault on the VGA side and the VGA warning LED stays on. The only way I have found to resolve this is a CMOS reset, however this only lasts for the first boot. Afterwards it develops a fault again.

My graphics card is a Palit 9800GT 512MB

[Rainmaker]

Have you updated the BIOS to the latest version? Reset the CMOS to get into your OS, download the BIOS update and apply. Reset the CMOS again and then set the BIOS back up how it needs to be (keep it at stock for now, if you normally overclock). See if that helps.