Hi,
I'm afraid I didnt get anywhere,
Funnily enough people keep saying do a bios upgrade, Chaps... read between the lines, You can't do a bios upgrade if you can't get it to the bios.
I got lucky once and did Bios upgrade, Tried it in the case, out of the case, tried 2 differernt Heatsinks (Why I'll never know.) 3 Different Graphics cards. a New Set of Memory ... etc... and it simply wouldn;t work.
It was possible if removed the battery for a few minutes and cleared the CMOS to get the POST screen, but after about 3 minutes it the UEFI would run slower and slower and then it would shutdown. (Got this to happen about 3 times. inbetwen days of boot cycles.)
the support i was offered took 3-5 days and I only had 7 days to get it working (under distance selling regulations with the reseller) so gave up and returned it.
The Motherboard I got from ASUS, worked instantly out of the box with now issues what soever with all the same pieces of hardware.
...it's ironic, because 7 months ago I went with Gigabyte with my AMD Bulldozer chips because the ASUS motherbaord I received was DOA. this time its the other way around.
i did suspect that the power supply wasn't man enough at one stage, but it was 700 watt. and the handbook says 500watt even the latest online manual still said 500 watt. Even using rig building sites, it said that I shouldn't need more than 434 watts...
All works fine with the new ASUS motherboard , so I can only deduce it was faulty.
If anyone ever gets this issue, it would be interesting to see what it is, or whethere there is a faulty batch or compatiblity issue with the i7-3820...
P.S. the i7-3820 is solid as a rock for its money, so glad i went with a socked 2011 motherboard !