My Gainward GTX titan black shuts down my computer when I try to play demanding games, i have tried two graphic cards, GTX 460 and GTX titan, and the problem doesn't seem to appear on those. i have a hp z800 workstation motherboard and a hp 1000 watt PSU
can you give us more specs about your PSU? maybe a link to a page about it?
Its the 1100 watt version, i think