When did I say you need a 2500w psu to run 4 290x's ?
Also that list doesn't show any pair of 290's .
I said that a 1300w will be good to be SAFE not that 2500+w is needed to run 4x 290x's , and i was talking about two 290x's , and no , two 290's can go up to 800w when they're at full load , plus an overclocked system it should go up to 930w
I never said that having 4 290x's is impossible either
No , actually it's not a waste of money , because not ALL games support crossfire , and you'll end up with the performances of a 290 on games that don't support crossfire , and actually getting a 290x is better than having two 290's at the moment , why ? because you'll have the possibility to crossfire a 290x LATER when more and more games support crossfireX and sli and games will be better optimized for those two technologies , you'll end up getting even more performance
The single 290 is not even overclocked
And yes it would certainly start a fire , or at least smoking
Why ?
Because the power supply won't provide enough power once again