Looks like a fairly standard board. If Gigabyte made it, then the hardware quality should be good. I wonder if the entire fault lies with a (assuming) custom BIOS?
Yes custom bios. However it flashed ok, I installed OSX ok. It didn't shutdown properly within OSX though and 50% of the time would restart.
Now it just continually restarts.
Also I have only found one other user who has had a similar problem, but apparently he had a faulty PSU. My PSU works great and I now have cinema display, so now I have my original gigabyte board working ok (no issues with restart etc.) although I'm unable to get my 7870 working properly. I think it may be an issue with the bootloader, as if I boot with the monitor plugged into mobo, I can see both HD4000 & AMD7870 in OSX, so the OS recognises the card ok, and I'm running 10.8.4 so it should work natively.
Edit: 7870 working ok now, just ethernet & app store to fix.
Edit2: All working on the gigabyte board now.
Quo have given me an RMA number but said I need to pay postage both ways. Not ideal but I don't have much choice so was happy to do that.
I then went to buy another board as backup (damn should of just got another mac), and I see they now only offer Fedex shipping (at least to UK). The problem is it's insanely priced ($150+) just to get the board shipped. My original shipping was only $29.99.
If they expect me to pay those kinds of fees for the RMA, then obviously it's not really financially viable to RMA.
I've asked them to clarify these shipping charges, so I'll see what they come back with.