Sapphire 7970 vapor x ghz 3gb will over heat and shut down
so i have had this graphics card for about a month or two and i just got a new cpu so im trying to run my card at max load, which i assumed could pretty much run almost any game on max settings smoothly, but when i randomly play games such as shogun 2, crysis, tomb raider, diablo 3 or almost any game, my card will randomly shut off and the temp is very high on the card when this happens. i uninstalled the drivers and reinstalled them and then it would work fine, but whenever i shut down my comp and then turn it on again, it seems the problem persists. it also seems like the graphics performance is lower than it should be, i expect to be able to play games smoothly on ultra graphics, but in some games its slow framerates or even tearing.. im not sure what to do, i heard that the vapor x is supposed to have great cooling so im not sure if its just that for some reason or the drivers? because i had terrible graphics performances before and all i had to do was uninstall and reinstall my drivers and everything was fine, now im not sure what to do. i have 8gb of ram and my mobo is asrock B75M - DGC LGA 1155pcie 3.0 sata 6gb, also my cpu is an i7 3770. i have read that mobo may be the problem but i really dont wanna put a whole lot more money into my computer than i absolutely have to seeing how much ive already put into it. please help and give suggestions.