Question Everything works fine but graphics card shows no output

[AnteGaro]

So i bought this pc from a guy and the PC worked fine for about a year,but than suddenly one day my pc didnt want to turn on to be more precise it just stopped showing output.The GPU is not dead all the fans spin and I did try the GPU in my friends PC and it worked,But the thing that confuses me is that my old GPU does work in my PC which is a ASUS HD 5850 1GB,At first i thought it was my PSU but i dont think it is because i tried 2 different PSUs ,one is my normal PSU that i use and thats a 550 corsair and the other is also a 550W PSU unless both of them are failing because both of them are used.I tried other methodes such as reinstalling windows and using the DDU software but none of them helped,I also checked if my mobo bios is up to date and it is.The PC is definetly not the best but i would really appricate any help fixing the problem ,Thanks!
My PC specs are
-AMD HD 7950 twin frozr3
-Amd fx 6100
-8 Gb dd3 ram
-550 corsair
-asus m5a78l-m lx3

 

[Ap0sGR]

Start by clearing the CMOS on your motherboard according to your manual (page 1-17).

 

[AnteGaro]

Start by clearing the CMOS on your motherboard according to your manual (page 1-17).

First of all thanks for trying to help,but it did not work no output on the monitor ,but i did notice that my gpu fans spinned very fast when i reseted the cmos ,idk if it means anything .