Power supply unit for ati hd4850


Jul 15, 2011
hi! i built a pc with the following details:
1.asus p7h55-m pro
2.core i5 (750)
3.2g*2 corsair ram
4.ati hd4850
5.120gb sata for OS
6.750gb sata for data

here is the twist,i powered it with a BFG 550w LS series. it lasted for two days then the pc went off in a middle of a movie. the main reson for building this pc was because i use it to video dj and i most of my videos are of high quality(mkv,mp4,etc)some of which are as big as 250mb. i changed to the default power supply unit that came with the case(400w). in the middle of a gig,the unthinkable occurred, the pc went off.then i realized it goes off when i begin to play a video.the power supply unit blew some few days later. right now I'm in a fix, i need your advice