I know this thread a bit old, but still within a decent time range...
You absolutely can overclock, forget what the people are saying here.
I have this exact motherboard, down to the brim, and the same processor, and I'm running at 4.2 GHZ, (Overclocked) on a stock cooler.
How did I do it?
Just monitor your temps, carefully, have good cable management, and alot of space in your computer and you'll do fine. Using a program like Prime-95 will test your CPU to near max on "Blend" mode, when using the "CPU Torture" option. Running prime-95 for a few minutes on a new Overclock setting, you should see if you have crashed or not. IF you have crashed, lower your clock setting or increase your voltage. If you have NOT crashed, you may continue to let prime95 run for a solid 10 minutes to see how hot your CPU gets. Your CPU should not get more than 65 degrees C if you feel like being comfortable, but things get iffy around 75 C.
I have the FX 6300, with EXACT same mobo, stock cooler.
(Not that it's relevant, but my GPU is the Radeon R9 270)
Power supply is 500W, shitty power supply to be honest, but it put's out decent enough wattage to run my parts.
GPU is NOT overclocked
CPU clock is 4.2 GHz, at 1.4 Voltage. (My voltage is high to prevent crashing, cause I hate crashing).
Running at a pretty high voltage like that, using prime95 with all my cores maxed at 100% load, my CPU temp maxed out at 59 degrees C.
My CPU, like yours, when clocked down at 3.6 or whatever it came as, was running idle at around 20 C~, now it runs at 35 C~ idle when OC'd
Just observe your temps and you'll be fine.