Galaxy is a cheap Chinese brand. I had a Galaxie GT 430 and it started having issues in both Win7 and Linux shortly after its 1 year warranty expired. In Win7 at that point it started freezing and then Windows would say video stopped responding, but recovered. In Linux occasionally keyboard and mouse clicks would suddenly stop responding completely, although, often the mouse cursor would still move. Eventually I got weird patterns on the screen at times or Linux nvidia module began saying that video was not responding during boot.
I replace the video card with an EVGA GTX 550 Ti with 3 year warranty several years ago and have had no such problems since then.
It could be something else, but that was the issue in my case. I5 650 3.2 GHz, 8 GB RAM, 1 TB HD and 80 GB SSD. Running 64-bit Win7 Premium or 64-bit Ubuntu 11.10 at that time (12.04 now). My 1 TB Seagate drive did begin failing sometime later, since replaced with WD 1 TB, but the above freezing issues did not happen at that time, Linux would simply remount its partition read-only to prevent further damage.
