Thanks for the input yeshuas and JabbaPapa!
Yes I do agree that I have chosen the most demanding version of Visa
and everything works fine when not playing Crysis or Flight Simulator X however I did some testing yesterday and this is what I got.
Played Crysis with SLI disabled and I was able to play for much longer (that is what makes me think its the PSU)
then I played Unreal Tournament 3 which is really ressource hungry and I was able to play that in SLI until I got bored.
I doubt its a problem with the game as other games will work, and the two games affected are from complete different development companies. I also made sure to have a friend of mine test both of those games in his setup and he was fine.
Did some research online and found people having similar trouble but no solution, but then again none of them have considered their PSU as being the problem.
Am I right to think that if the GPU requires 400W to work, that it would be 400W each of them making the grand total of 800W which would take all the power possible from the PSU and cause the crashes?
Sorry for the questions and confusion, I'm just trying to find the cause of this, because I can't believe that with that type of setup that I have put together I am having performance problems
Thanks again for the input!