Hi mat,
Not every single FX 6300 cpu is the same.
How well it over clocks, or does not in some cases depends on what fabrication plant the cpu was made in.
It also depends on how good the silicone disk used to make the cpu`s in quality was when they etch the cpu and build it up on the silicone disk, substrate.
And the brand and type of motherboard, it`s brand, model number, chip set used on the board.
Can also effect how well an FX cpu overclocks
It also depends on how you are doing the overclock.
If you are having problems overclocking the CPU.
And you are just using the cpu multiplier.
Make sure that your memory clock stays at 200Mhz relating to memory.
Or lower the speed the memory is set at to a lower working speed, other than its maximum or it`s xmp mode.
Often it`s not the cpu to blame but the fact the memory is stretched too high in speed that prevents the board from posting.
You should be able to get the cpu up to 4.3Ghz with a core voltage setting of about 1.35v to 1.38v
In your bios make sure you turn off the auto turbo feature if the bios has the option.
And also turn off the cool and quiet option in the bios.
If both are enabled in your bios they will hinder your manual overclocking.
C6 state enabled.
Also check if you have a cpu shut down temperature in the bios options of your motherboard it is not set too low in Celsius or Fahrenheit. Remember the more voltage to the core, and overclock frequency set by the multiplier the hotter the cpu will be.
Keep an eye on it.
But your H80i should take care of it without any worries.