I just built a new system, salvaging my old GPU and PSU. The only problem I'm having is that sometimes the whole system will freeze and I'll have to force restart. It usually happens while playing games, but not necessarily. On the second day after I built my computer my old 750w ATX Ultra PSU failed and I purchased a different PSU but the problem persisted. The event viewer didn't record the critical error with the exception of Kernel-Power 41 until the most recent crash - nvlddmkm error 14.
On top of that dxdiag is telling me I have 4gig vram when I only have one. I tried to test my GPU with OCCT(an older version than current to get the functionality I needed) and it told me I can't run the GPU memtest because I do not have the lastest drivers. I then uninstalled my nvidia drivers, ran Driver Sweeper in safe mode, reinstalled the latest drivers from the nvidia website and I still get the same error from OCCT.
I've also checked my HDD for errors and that turned up clean.
Temperatures are 28-40C across the board. Only time I've seen them rise above 40 is while performing a stress test and that was up to 51C max.
My specs are:
Win 7 Ultimate x64
Gigabyte GA-970A-DS3 motherboard
AMD Phenom II X4 965 (Black Edition) 3.4 GHz Quad Core
G.SKILL Sniper Series 8GB (2 x 4GB) 240-Pin SDRAM DDR3 1866 (PC3 14900) Model F3-14900CL9D-8GBSR
NVIDIA GeForce 9500 GT
WD Green WD5000AZRX 500GB HDD 3.5", SATA, 64MB Cache
600w Thermaltake PSU
2 120mm led fans
It is probably the WD Green HDD. I had the same issue; My system would freeze after about 30 minutes of use, or under intensive loads. The WD Green is not good for storing an operating system. After switching from the WD Green to my SSD, the issue completely went away, and my system hasn't frozen since. Try a Caviar Black or for optimal performance, an SSD.
The graphics card? Currently it's at 37C. The range for it normally is between 31-40 C, doesn't usually go higher than that except when running a different OCCT GPU test, and it went up to a max of 52C.
As far as the HDD goes I'll replace it this friday and hope that fixes it.
I figured I'd describe what happens in more detail. Before the crash everything runs fast and smooth, I don't notice slowdown of any kind. It crashes suddenly and completely. Everything is locked up, my mouse won't move, the pc won't respond to keyboard commands(or at least nothing on the screen changes). The latest second of sound in video games will loop BUT a couple times I was on skype when it happened and I could still talk to the other person. The HDD light is dead. The only way to get the computer to unlock is to force it to restart.