black screen after windows logon

So i bought a pc for 300$ with this specs I5 2320 r9 270 ih61m 2x4 Gb Kingston 1333mhz Psu 460w. I was using it fine for a week until yesterday. I was playing Gta V online and i saw screen flickered once i ignored it, after 15 mins another one. Screen started going crazy until windows crashed. I...