Need Serious Help pls SAPPHIRE7970 cant play any games

[blackace333]

Hi Bros and sister , i bought my computer yesterday but after fixing the computer parts its seem wierd . After installing window 7 OS sometime like 50% when i startup my computer it show window are starting up it hangs there with the win7 logo not moving . the 2nd MAJOR problem is after i update all the drivers when i go to skyrim it start the game perfectly but after less than a min , My Monitor turn black with a message saying no signal when i can still hear the game sound than suddenly i hear the sound like GRRRRR hanging sound and the computer restart, Sometime grey screen with white strip , or it closes skyrim and a message popup saying something like display driver is not responding but was recoverd . Is there something wrong with my computer built ? GPU SapphireHD 7970 OC MB ASRock Fm2a75m-DGS PSU seasonic M12 bronze with 650W . Does anyone know what is the possible problem ? This is so depressing I somewhat felt like injustice like i got scamed from seller without know what cause such problem

 

[Xttony]

Do a clean install of the catalyst control center.
Make sure that the temperatures are not too high on any component.
Test your graphics card on another system.

 

[weaselman]

Did you plug the extra 12v Pci-e power connectors in on the back edge of the graphics card.
And did you also plug in the eight pin power connector to the motherboard located next to the cpu socket ? That sound is like the Graphics card saying it does not have enough power to run it when a game is launched and running as the card it requires more power in 3d mode, when you play a game or something using it. Note the two eight pins on the card must have power connected to them.
See picture.
http://www.overclockers.co.uk/popup_image.php?prodid=GX-062-HS&imgID=6