Custom Built Computer Issue

I am having an issue with a computer I recently built for my company

Here are the problems:

-BSOD at night when the system is idle
-BSOD randomly atleast 2-5 times a week when system is in use
-"Weird" video card issues (screen colors change mouse starts to stutter then whole computer freezes still displaying image on monitors but have to hard restart the computer) (This happens once in a great while)
-Computer just powers off as if it was unplugged from the wall (Not happening anymore)
-Windows updates especially those for Office 2010 seem to fail repeatedly

When these problems started the first thing I did was remove the overclocking on the system which did not seem to solve anything.
All the temps of the hardware are well within safe range even under a load
I have ran Prime95 for 3 hours and the system did not BSOD I ran SuperPI completed in 9minutes 30 seconds with no issues I ran FurMark 1.10.0 with no issues Windows memory test reports no errors with memory

System specs:
Cooler Master HAF 932
Corsair CMPSU-750TX 750W PSU
Asus Rampage IV Extreme MOBO (Latest bios)
Intel Core i7-3930K Sandy Bridge-E 3.2GHz (No longer OCed)
G.SKILL Ripjaws Z Series 32GB (8 x 4GB) 240-Pin DDR3 SDRAM DDR3 1866
OCZ Vertex 3 120 gig SSD
Nvidia Geforce GTX 560 Ti
Lite-On disk drive
Corsair H-80 CPU cooler
Windows 7 Pro (64 bit) SP1
Joined to a Domain

Computer is used to run Autodesk Inventor 2012 for 3D modelling the random BSODs occur sometimes when the User is using Inventor other times it happens when they are checking email

If anyone has any ideas please let me know I think its either a bad RAM stick or something faulty with the Windows installation but before I go testing the 8 ram sticks individually or re installing windows I wanted to see if anyone else had any ideas