Is 75 degrees too hot for a desktop when gaming/rendering?

Whenever I run Minecraft and Skype and Chrome all at once, usually just MC + Skype, I tend to get CPU temps in the low to high 70's in celsius on my CPU. My CPU is a AMD 8 Core FX 8320 at 3.5 GHz. HOWEVER, my PC is VERY easy to cool down. As only after about 5 minutes of turning Minecraft off, my CPU stays around 20 degrees celsius. Is this good or bad?

Very good. Max temps for most is above 100 C.

75 c is normal and acceptable limits on AMD CPUs. It's high and you definitely don't want it running at that temperature 24/7 but for a short period it is okay.