Dual BIOS LED disco, P67A-GD80 (B3)

Question

I've just set up a new system, exercising extreme caution, reading manuals, checking forums, and taking all measures not to mess things up.
When I finally buckled up and hit the start button, things seemed fine, the fans were running and I was greeted by the BIOS setup interface. A couple of minutes after browsing the menues, checking temperature and stuff, but without actually making any changes, screen froze and the system ceased to respond to mouse or keyboard input, even ignoring my desperate efforts to restart or turn off the machine using the front panel buttons.
After turning off, using the PSU-switch, I found that at least it did NOT smell burnt, so I gave it another try. This time the fans started again and the GPU-fan sounded considerably louder than before, actually noisier than the average vacuum cleaner, but nothing showed up on screen at all. Just darkness and the terrible howling from the GPU. Again, the front panel switches wouldn't kill it, so I started to think about what could have gone wrong. After thinking for a minute or two the system just died by itself.
I couldn't restart it immediately, but after a few minutes I could turn it on. Still nothing on the screen though.
I've reassembled the machine, checking cables and stuff, trying different RAM setups, cleared CMOS, removed and reinserted CMOS battery, but still just get one beep and eternal darkness on the screen. The motherboard buttons for on/off and reset won't turn off/restart the system. I notice two solid lights on the CPU Phase LEDs, telling me that "CPU is in 2 phase power mood", but I really don't know what that means.
Also, the Dual BIOS LED goes disco on startup, altering between fast blinking and slow (1 sec) blinking to finally end up with a solid light, telling me the primary and secondary BIOS failed.
Have also tried to start the motherboard with everything disconnected except PSU and a RAM-card, even without GPU, just to see if the moderboard's on/off and reset buttons responds after being turned on, but everything except the fans and leds seem dead.
Anyone got any idea of what's causing these problems, or what I should do to get wiser or even make things work?
Is the CPU just dead? Motherboard short circuit? Some kind of BIOS-black out?
Is the non-responsive (well, it responds to on, but not off) on/off and reset buttons on the motherboard a sign of something?
This is my brand new, not-working-at-all system:
Corsair Graphite 600T Midi Tower
Corsair TX V2 850W PSU
MSI P67A-GD80 B3, Socket-1155
Intel® Core™ i7-2600K
Antec Kuhler H2O 920
Kingston DDR3 HyperX 1600MHz 16GB
Sapphire Radeon HD 6970 2GB GDDR5 (x2, have tried with just 1)
Corsair SSD Force Series™ 3, 240GB
Sony Optiarc DVD±RW Writer, AD-5280S

Answer 1

Yeah, I tried that, but I'm not 100% sure I properly cleared CMOS. Did change the pin from save to clear data and removed battery, but the battery might have been removed too short time (20 sec). Also, the power cable to the mother board was still connected (the PSU was shitched off though) which I later read it shouldn't be while clearing CMOS.
Still, the Dual BIOS LED goes solid, so I guess the mother board is bricked.
I'm really not sure what to do now. Let's say I buy a new mother board and it works outside the chassi, it could mean that the old mother board was defect from start, or
it can mean that the chassi is defect. To be sure I have to try the new mother board in the chassi, and possibly destroy it. Feels like this trial and error method is going to cost me a few mother boards.
I do hear the single beep when I start the computer, so it POSTs I guess. Does that mean the CPU is NOT broken? I've heard that the CPU is needed for the POST.