fastertove :
I have never heard of a PSU actually burning down a house. It's popossible, I guess.
It is unlikely, but i have seen sata connectors melt and smoke. I have seen numerous psu's explode in puffs of smoke (used to work for a pc manufacturer in building, testing, warranty), often when they explode they damage other components like the motherboard. They may also not produce their rated power, or not produce clean power. Many of them will work but not last more than a year before failure (like most of the "Ultra" brand psu's). So don't skimp on the psu.