XxStarChaser :
Ok. But I still have some questions (I hope I am not annoying you). Is it risky to underclock/undervolt? And should I use a closed case?
And if this situation keeps going, I'll buy a 212x for that 6C difference. Thanks for your helps.
No worries, if your fans are clean of dust closed case should give better airflow and keep things cooler.
I am a bit biased, but I've been happy with my
AIO cooler, you may want to consider that (or something similiar) if you are looking for new cooling solutions. Basically it uses a closed loop of cooler liquid to pull heat from the cpu to a radiator which with an additional case fan (that for your case could be placed in the fan slot on the top of your case) can blow air through the radiator right out of the case.
And to clarify the option of underclocking/undervolting:
Underclocking is the opposite of overclocking, its reducing the maximum speed at which your cpu can run
Underclocking can't do any damage other than making the cpu slower, but poses 0 risk of any physical damage. Its kind of like forcing your 8350 to act like an 8320 for example.
Undervolting is reducing the maximum voltage the cpu can draw from the motherboard, thus under stress the cpu would consume less power and produce less heat.
This can't cause any permanent physical damage and actually in theory can extend the lifetime of your cpu by reducing its heat generation, the catch is that especially for a high frequency part like the 8350 you probably can't undervolt much if at all without underclocking as well. This is because depending on the load the cpu will run at a different frequency, as load increases so does frequency. Higher frequencies require higher voltage to keep the cpu stable, thus more heat. if you try to go to a frequency without sufficient voltage you'll bluescreen. The difficulty is that the voltage required for a particular frequency is unique to every cpu, even those of the same model.
For more details on undervolting I'd recommend this
post. It's 9 years old and won't help for figuring out how to actually undervolt your machine, but it gives a good overview of undervolting, its benefits, and goes through the general steps to undervolt.
That was longer than I originally intended, hope it helps.