WTH is happening here :/

[GT7R]

Just got a mini DP to DP cable and connected it. PC wont start but just make a quiet squeaking noise

Then the only way I can turn it on is if I disconnect the cable from the GPU and wait for about a minute. Then connect the cable after it's fully booted - it works. But then suddenly I see then it has decided that it sees only 8GB of RAM (?!) instead of the full 16.
...

Edit: Solved, A dead board.