Gigabyte GA-EX58-UD5 -> only Clr CMOS lit on first startup

Hi folks,

Have just setup a new pc with the following spec in an Antec 1200 Twelve Hundred case:

Intel Core i7 920 2.66Ghz
Gigabyte GA-EX58-UD5 Intel X58
Sapphire ATI Radeon HD 4870
OCZ Reaper 6GB (3x2GB) DDR3 PC3-15000 (1866MHz) Tri-Channel
Western Digital Caviar Black 1TB SATA-II 32MB Cache
OCZ StealthXStream 700w Silent SLI Ready ATX2 Power Supply
Sony Optiarc DRU-860S 22x DVD±RW SATAl

On first startup, I hooked up just 1 mem stick (2gb) and left out the Sony optical drive.

On powering up, all I see is the Clr CMOS switch lit up and nothing else. None of the fans startup, no other leds just the Clr CMOS switch,

I've checked the following:

- MB is seated properly with all grounding posts in place
- Power cords secured into MB (2x4pin for the cpu and 20+4 pin for the MB)

Am at a bit of a loss as to what I could try and do next since early indications suggest that no power is being supplied to the mobo or even the cpu.

Any suggestions / help would be greatly appreciated.

actually, it doesn't matter which way you plug the power switch in on the motherboard.... So that means it was a different problem...

Interesting, as this is exactly what I thought to begin with. But the only wire connected differently when it worked was the power switch, hence my assumption.

I suppose rebuilding the pc from scratch a couple of times resolved any loose connections, grounding issues.