Ok so I've just built my first computer and have got it running, here are the specs:

Asus P8Z68-V PCI-E LX Motherboard, Intel Core i5-2500K, Patriot Memory 8GB (2 x 4GB), Viper Xtreme Series PC3-15000 1866MHz CL9 Division 2 Edition Memory (PXD38G1866ELK), Gigabyte ATI Radeon 6850 820MHz 1GB PCI-E HDMI OC Windforce 2x 500w Ezcool 24pin psu as standard.

The only thing I haven't bought new is the hard drive, it's a 250gb that I removed from an Acer Aspire M5100 that I was using till now with no OS Problems.

On start up it runs fine but is unresponsive after the GRUB menu disappears to load Ubuntu (Oneric Ocelot). The keyboard lights then turn off and the screen eventually returns that there is no signal.

Is there anything that I could be missing from building? (This is my first attempt at building my own PC)

Any input would be appreciated, thanks !