|I might be able to help, i might not.|
Chances are you have probably tried this already.
Not only that but it looks exactly like what Richard59 said just a few alterations.
I surged my computer a while back, everything screwed up.
I took it apart, replaced everything with other pieces, nothing would work.
Turned out that the reason reinstalling everything didn't work was majorly because i just had knocked one of the ram sticks paritally out whilst re-screwing the computer. It was almost as though the RAM was shorting the computer -- turns out it was. So i put it back in properly, got it working and everything, put its case on -- stopped working.
I had to replace the graphics card, the RAM shorting problem ended up screwing my graphics card to.
So my main reccomendation would be -- Make sure everything is connected properly.
Do exactly what Richard59 reccomended too, remove all the unimportant stuff and try it then, if it works, replug it all one by one.
Its a slow process but it sure beats having to replace a $500 graphics card and a $80 4GiB RAM stick :P
Goodluck, hope this helped.
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