Hardware faultfinding - please help

[Gomaku]

Hi

I have recently purchased parts for a new machine, when I boot up the device the fans come on but no display is sent to the monitor, to eliminate the graphics card it has been detached and I am running graphics straight from the motherboard, still no luck. In addition no usb external device is powered. the HDD and DVD ROM are powered. No beeps are sent from the motherboard nor does it shut down it just runs with no image. I have reset the CMOS and tested the PSU voltages. I have also changed cables, changed monitors still nothing. I had this problem before and returned the motherboard it was confirmed faulty and replaced, this is the new motherboard - have I been unlucky and received 2 faulty motherboards or is something else at fault here?
I've read the troubleshooting guides and followed as much advice as I could, I've run out of ideas at this stage and a 2nd opinion would be muchly appreciated.

Thanks in advance

 

[RJC]

What are the full specs?

I assume you have all the power connections connected like the 4 or 8 pin for cpu power and tried different memory combinations.

 

[Gomaku]

Hi, yes I've made sure all the connectors are in place, if any of them are missing the machine won't boot up at all.
the specs are:
Asus GeForce GTX 670 DirectCU II 2048MB GDDR5 PCI-Express Graphics Card
Gigabyte Z68AP-D3 Intel Z68 (Socket 1155) DDR3 Motherboard
OCZ ZS Series 650W '80 Plus Bronze' Power Supply
Corsair XMS3 8GB (2x4GB) DDR3 PC3-10666C9 1333MHz Dual Channel Kit x 2
Intel Core i5-3570K 3.40GHz (Ivybridge) Socket LGA1155 Processor
Western Digital Caviar Blue 1TB SATA 6Gbs 64MB Cache WD10EZEX HDD