You're tripping a breaker. The short gist of tripping breakers is that certain parts of homes are wired together to breakers, often times single high-draw rooms (like a kitchen) are wired to a breaker just for that room, but often a couple or even multiple low-draw rooms (like bedrooms) are wired to a single breaker. So if you pull too much power through a breaker it will trip and shut off power so other components don't get damaged.
I'd try using an outlet in a different area of your house. If that still causes the power to go out I'd remove the graphics card and try again. If even that doesn't work, I'd think it would be time to figure out what's pulling so much power (aside from the computer) that it leaves so little wiggle room.
I can't possibly see how a pc is shutting down the whole house, you should only be tripping one circuit. I it is the main tripping the breaker for the room with your pc will need to be replaced.
I know, my roommate in college had some friends over and had 5 gaming desktops and space heater and 2 70s era mini fridges all on the same breaker, I bet you can figure out how that turned out. They couldn't figure out what happened even after I explained it to them. I told them its electricity not magic it has to be regulated and have a cutoff point or the current can overload the wires in the walls and set fire to them.
Try working for a political party in a rented former storefront as an office.
Why yes, it's perfectly OK to daisy chain 6 cheapo power strips and ungrounded extention cables to a 3 Xerox office laser printers, 8 thin clients running off an Opteron server, 6 laptops and a video projector, what could possibly go wrong...
*cue me noticing the smell of melting plastic and ozone gas as a que to locate the inevitable electrical fire*