Motherboard help

[saltynay]

Background info:
Installed a new mobo last week its an Asus striker 2 Formula and was a B-grade RMA' board (I couldn't resist it was half price of the retail). Everything worked fine for the first 4 days then one morning I woke up to a black screen. I originally thought the Gfx card had gone and wasn't to annoyed as I had just bought another for an Sli pair (which arrived today).

Problem
I am not getting an display from my computer at all so can't run memtests or bios. My computer does start up and sounds as if everything is good but no signal is ever sent to the screen. I have tried;
Changing monitors
Changing graphics cards
Changing pci-e x16 slot 3 times with both cards

I am a bit stuck now should I call up Asus and have a little rant or should I do the extremely tedious and seemingly inevitable task of taking out the mobo and swapping it for my old one P5B deluxe. Bear in mind my case is extremely compact, overfilled and to take out the motherboard involves taking out every other component. Just wondering if anyone has any thoughts of what else to try....

Ps the system speaker does go off if I try to install the gfx card without the 6pin plug which surely shows it detects something......

Edit: The strangeness continues either I was hallucinating or my computer just booted into the bios however I turned it off and on again (to install the other graphics card, I am an impatient person) and now nothing appears again (no signal still). I didn't change anything when installing the sli except the obvious card in socket manoeuvre and the 6pin plug in the back of the card. If I wasn't hallucinating then I now know the one that came today is definitely working as well as my old card which I am fairly sure is..... I have tried another 12 times swapping pci-exp ports and cards and no signal must of been a dream of it working before.

[peterb]

Something not plugged in properly
Defective PSU (not familiar with BFG)
Defective Mobo - if it boots again make a cesrful note of any speaker beeps.

Only realistic way of testing is by substitution. A grade B board should be the same standard as a grade A, but will be a refurbished or repaired unit - probably previously returned as faulty, and therefore cannot be sold as new. However you still have warranty rights on it if it does prove to be faulty.