Thanks guys i will try with another psu.

I have one 6 and 6+2 pin connectors. But my psu is only 500W so i guess is not enough.

Well, I've looked at one site: game-dabate.com and that's what i found.Recommended PSU : 450 Watts & 28 Amps mine has two 12v rails with 18amps im not shure is it enoug.And this one GPU Power Requirements: 140 Watts (I have no idea what this means)I'...