hp pavillion m9150f freezing issue

[Paragorax]

recently i found a pc in the trash, everything works fine, ive flashed a new copy of windows on it, replaced the hard drive, (which was failing). things are good. fast pc. but at random times, the screen will flicker on and off, then the mouse and keyboard dont respond. sometimes the monitor turns off, other times it stays on but flashes intermittenly, one time it went black and showed nothing but these weird vertical red lines and dots, like a pattern on the screen. it dosent seem to do this in safe mode, but even if i let it boot normally and leave it sitting doing nothing.. it still happens. what am i looking at? graphics issue? i dont think its the monitor, but its got a nvidia geforce 8500 in it. ive even updated the graphics drivers. still no idea.. any help?

 

[popatim]

replace the graphics card I would.