sorry if im posting this in the wrong section im new here. well during december this year i built a pc. its only been about 5 months of owning it. its been working great until about 5/24/12. I first noticed my computer was randomly shutting down while playing games such as Saints Row 3. especially with explosions. my monitor would say going to sleep. then my computer would restart or it would turn off and i would have to turn it back on. when i am browsing on firefox or sometimes when i just turn it on or if its been on for maybe 10 -30 minutes it will freeze and i will have to restart it. i ran windows memory test twice and there were no errors. at first i thought my computer was overheating since it is getting warm outside now so i got speed fan and my temps were normal. sometimes my computer will work for hours of gaming and other times i wont be able to play for 2 minutes. i got Furmark and tried to do a stress test but my pc restarted instantly when i tried to run it and my monitor said going to sleep. i did a disk check and that came back with no errors. i tried to do a defragment and a virus scan but my computer would freeze before they could finish. i haven't downloaded anything recently so i don't think i have a virus. i installed itunes because i got a new ipod and that's when i first noticed that my computer would freeze while putting songs on it. i could still play games though. i ran prime 95 for a while and that came back with no errors. i also downloaded occt and tried the gpu test with the same results as earlier with it restarting or completed powering down.i then tried to test my psu and that made my pc shut down also. i also updated my gpu drivers when i started noticing the problems and it didn't help so i uninstalled them and installed the drivers that came with my card. that didn't help either. i updated my motherboard bios and that also didn't help. yesterday i after redoing the gpu drivers i tried running saints row 3 and my computer blue screened and i took a photo of it but i don't know how to post it here if you even can. i was ready to take it to the pc shop but i decided to try asking here first. i also have noticed when i first got my computer that when i played games i could here a screeching sound coming for my pc. i looked around online and decided that was just how the card runs. the newest computer that i have to this one is about 6 years old so i didn't really know how they work now. ive looked online for the past couple days looking for a solution but i haven't found one so i thought i ask. thanks for any help in advance.
G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL8D-4GBRM
Seagate Barracuda ST500DM002 500GB 7200 RPM SATA 6.0Gb/s 3.5" Internal Hard Drive -Bare Drive
EDIMAX EW-7128Gn PCI Wireless Adapter for PC and Mac
GIGABYTE GV-N560OC-1GI GeForce GTX 560 Ti (Fermi) 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card
GIGABYTE GA-970A-D3 AM3+ AMD 970 SATA 6Gb/s USB 3.0 ATX AMD Motherboard
Sounds like either PSU or GPU. Have you confirmed that the fans for each are spinning? Your CPU sounds fine since it runs Prime95 and that wouldn't be that stressful on a PSU. Gaming or GPU benches (especially Furmark) do put a big strain on that icky PSU. GPU-z will also give you temperature readings for the GPU, try that as well.
So first I'd replace that Cooler Master thing with an Antec, Corsair or Seasonic PSU. Then if the problem persists cash in your warranty on the 560ti with Gigabyte. This assumes you've tried reseating the card and checking all the power connections, etc.
And you could try the 560ti in another computer (that has a PSU that can handle it of course!).