GPU diode too hot on the Apple?

I'm worried that my GPU on the IMac is too hot.

When I play Minecraft it sometimes gets up to 84 degrees hot, is that normal? Or harmful to the Imac?

Information from Apple pc:

iMac (21.5 inch, mid 2010)

Processor: 3.2 GHz Intel Core i3

Graphics card: ATI Radeon HD 5670 512 MB

Yes, in the long run this is definitely harmful. If it is possible, it could be cleaned up. Maybe the ventilation will work better then.

How to clean The fan?

Yes, if it is possible, because to open it, just remove all the dust. Possibly also on the fans.

You can open it, but I'm too afraid that the pc will break

there are 2 screws at the bottom

Maybe there's a YouTube video about it. Because that's the only method I can think of.

OK