After thinking that one of my cores is broken or something running hotter than the others, I used CoreTemp to change the Tj Max value to +1000 to see how hot it will let me go on a stress test, and apparently Core 0 is running at 1065 degrees while the rest run at 65. The problem is, once it DOES hit that amount, the CPU clock fluctuates between 800MHz and 3214MHz as well as the voltage dipping and the temp doesn't rise any higher. Its obviously an attempt to cool the CPU down, but its not needed as its a false reading.
It is very noticeable in games as they start to stutter lag when the core speeds dip.
If the speeds change in-game then yes you will see some deterioration in gameplay, Obviously the lower the clock speed gets the slower the FPS etc etc I believe you have your CPU running on automode so when you are doing hardly anything (idling) your CPU's speed is low, whereas if you are doing something intense then it will speed up. Now you almost definitely have a faulty temperature sensor, it could be a bug on the program you are using or a motherboard sensor is deficient. I recommend that if you don't want this to happen adjust your power settings and for temperatures check in the Bios or download another program such as HWMonitor or SpeedFan.