0) reinstall drivers - not always the latest version is good btw, check the forum for most stable version for your card
1) get the ANY overclocking off (cpu, video, RAM etc)
2) if it dont helps clean the video cooling system (radiator and cooler) from dust, etc. Get the radiator off and replace the conductive paste on it. If there are some "conductive scotch" THROW IT AWAY. Get the right paste (MX4 for example).
3) if the blue or black screen happened again just replace the power supply on more powerful model.
i'm running 1kw hiper and 3x850W TX's from corsair so I could recoomend the same models to you...
Hope it helps.