Random BSOD Crashes

Hi all,

For quite some time now, I have been experiencing a lot of BSOD crashes on my PC. For most of last year, I would get maybe one BSOD every 1-2weeks, sometimes less. The most recent hardware upgrade I have done was to upgrade my Nvidia GTX660 graphics card to a GTX670. The GTX670 has been in about a month and a half. My PC ran fine normally with this new card (well, by normal i mean i was still getting the odd BSOD every 1-2weeks), but after about a month with the new card, i started seeing a marked increase in BSOD (at least once a day). I do not O.C my system. The crashes are occuring randomly. There is no particular situation that makes them occur. Sometimes i would log onto windows and get a crash within 5mins, sometimes i could go hours without one.

Reading through the BSOD dump files, i see that the predominant items are hidclass.sys, hal.dll, ntoskrnl.exe, and ntkrnlmp.exe. The errors seem pretty vague and dont really narrow down a culprit.

Here is my system config:
OS: Window 7 64bit
MB: Asus P8Z68-M PRO
CPU: Intel i7 2600K @ 3.40GHz
RAM: 4GB DDR3 (2x2GB Corsair CMX6GX3M3A1600C9)
Graphics: Asus-Nvidia GTX670 (not O.C) running v310.90 driver
PSU: 775W
HDD: Western Digital 1000GB, Patriot Pyro 240GB SSD (OS installed on this).

In order to fix the problem i have tried the following:

- Update all drivers to their most current version
- Update all firmware including motherboard to their most current version
- Complete re-install of windows 7
- Run memtest for over 8+ hours. No problems detected.
- Run checkdisk, scan disk etc. No problems detected.
- Checked MB, CPU and graphics card temps - all okay.
- Re-seated all RAM sticks and graphics card. Checked pins. All seem okay.
- Checked all power cables to see if they were loose. All okay.
- Disable the 1000GB hard drive. Error still occurs.

Recently i have taken out the graphics card completely and have my PC running off the onboard VGA driver. So far its been over a day without a crash, but the crashes are random so its not a guarantee that the graphics card is causing the issues. I am planning to put my old GTX660 (which works fine) to see how that goes.

I just wanted to know if there's any other tests i should run to detect problems? Maybe theres not a problem with my GTX670, and perhaps its the motherboard? Maybe the PSU is stuffing up or not supplying enough power when i have a graphics card installed? How do i tell what the issue is without going out and buying new parts? I would like to avoid buying a new PSU, or motherboard if they are not the problem.

Thanks guys!