The thermal specification (TCase) of the Intel® Core™ i7 processor I7- 2600K is 72.6°C: http://ark.intel.com/products/52214/Intel-Core-i7-2600K-Processor-(8M-Cache-up-to-3_80-GHz)
This a number established by Intel® as a point of reference in order to understand what could be expected as per normal processor temperature.
Anything from the Tcase and below will be the expected temperature of the processor in normal use, anything that doesn't stress out the processor (watching movies, burning CDs, browsing the internet, creating documents, etc.) When the processor is stressed out meaning that you are running heavy processor applications that take control of the CPU or uses it at 100% the temperature will go beyond the Tcase. It can perfectly reach 90 to 95 degrees and the processor will still be OK. The cooling fan is in charge to keep that temperature there.
If the processor temperature reaches 100 degrees or more it will send a signal to the motherboard to shut down to prevent mayor damages and most likely it won't be possible to turn the computer back in until it cools down.
When accessing the BIOS, the thermal control features are disabled and due to this, the processor’s temperatures raise and are usually higher than within the Operating System where the thermal control features are enabled.
Furthermore, we do not validate third party software testing results since, it is very common for them not to be fully optimized for the specific processor model in use (these tools are more generic), being very common for them to provide inaccurate results.
If you would like to test your processor’s functionality, we recommend you running the Intel® Processor Diagnostic Tool which can be found here: http://www.intel.com/support/processors/sb/CS-031726.htm
According to the system behavior description presented, the processor is currently running within specifications.
Just to echo the good advice from Intel that although these temperatures seem rather alarming to us, it's not very hot when you are a piece of silicon.
The typical retail cooling solution is designed for real-world use which very rarely sees all cores driven to the maximum, so when you run something like Prime you can overheat a perfectly good setup. Modern CPUs are designed for this and if driven too hot will automatically take precautions to slow themselves down to avoid damage. In order to allow stress tests like Prime to work without causing alarming temperatures Intel would need to ship much bigger heatsink solutions, which for 99.99% of the people is a waste of money and metal.
Temperatures in the 80s and 90s are quite normal when modern CPUs are understress.
and 50-55 celsius while idle sometimes is good too? Thing shoots up to 95-97 celsius when I open league of legends and browse the internet at the same time. From what I have heard from other people it sounds like the heatsink isnt touching properly. because even thought its hitting 97 celsius the heatsink itself is cool and not warm or hot. So for the next couple days I am gonna use my gaming rig to just browse the net. I ordered and aftermarket HSF the CM 212+. make sure I have proper contact when I install it this time.
What cooling sulition are you using now , Air or H2O , I would sugest looking at some of the H2O Products that cousair makes , I have two High end machines , that I just could not get the temps that I was looking for and I installed coursair H2O sys in both , they have been running at 40C for over a year now , temp never goes above 55C no matter what I throw at it .