Hello. This is my pc specs, Intel i5 2500, Nvidia gtx 480, everest 600w power supply, 8gb ram, window 7 64bit. Since 2 days my graphic card had problem, I can see the red dots on my screen and also was shutting down unexpectedly give me error about graphic card, it was on it last days, so today I bought Saphire Radeon R7 260X, but I couldnt install it because the cable it porvided could not fit my power supply, then I try to use the nvidia cables on it and my pc was like On and Off after 1 sec everytime I start it, I did a lot of troubleshoot, now my pc wont start at all, I think my power supply is the problem, Can you guys tell me which power supply should I get that would fit them or is it any other problem, I would be very happy for any help. Thanks.