Hi Sylvia
I was having the freezing problem from Friday 28th June until Friday 5th July when I posted my original response in this thread. Since that post, we have not had the freezing again so it seems the system may have stabilised as I have described that it seems to do after any changes to the hardware configuration. Prior to my post it seemed to freeze every couple of days.
However as far as the video goes, before I added this card which came from our previous PC, (early 2012) the stability of the system was the same except that obviously the video performance was nowhere near as good.
Board: DZ68BC CPU: Core 2700K BIOS: 39
RAM: Kingston Hyperx 4 X 4GB Video: Gain GTX 460 1GB Latest Drivers
SSD: OCZ Vertex 3 128GB MAX IOPS PSU: Antec 1200 Watt
OS: Win 7 64 Bit Ultimate SP1 Fully Updated
SSD Also has latest firmware.
Hope this helps you look into this.