My intel i5 3570k is running 100% load nonstop with nothing present

Recently, I built a new computer with the specs in my signature but incase it doesn't show (I'm new to the forums and made the account recently) I would like some advice as to what is going on. I've never had problems with the cpu used as its been in my last build and used to idle 34c like nothing. Presently, I see it as idling at 37-38 which is fine but that is only in bios, the very moment windows 7 desktop is present it suddenly hits 100% load with nothing running and hits 95c and rising! I get scared and quickly shut it off. This is the second time now, I've tested the power supply, had the outlet changed, bought a nice surge protector, checked to see 12v reading on bios, it checks, and have even replaced the motherboard and cpu now.. Please advise. It was working just fine before. I feel as though some odd thing is causing it to hit 100% load instantly. Sorry if this has an obvious answer or is even just oversight.. The cooling is not the problem as I've got 3 120mm fans, 1 140mm fan intake and 1 200mm fan and 1 120mm fan as exhaust. Even built a negative pressure in the case to expel heat faster. How do I fix this?            
System:
CPU: intel i5 3570k
Cooling: Stock
GPU: XFX DD Radeon HD 7970 black edition
PSU: XFX Pro Series Core edition 850w
Motherboard: Asus Tuf series Sabertooth Z77
Case: NZXT Crafted series Phantom
Case Cooling: 200mm fans, 140mm fans, 120mm fans
HDD: 500gb hard drive total

To make it easier:
Its running the stock clock of a 3570k at 3.4ghz
Has the stock intel cooler, which I've checked and it appears to be making direct contact
The power supply was tested to being fine and in great shape. Also recently bought so it isn't an old one
Mobo temps are 28c-30c


On a final note, can anyone point me in the direction of a guide to OSX for this aha. I've seen people do it on this board but no guides:/