Remove the Video card........ and then do everything.
If you have a blower, I'd suggest, using some non conductive pencil like material/object to stop the fans from spinning while you blow the dust and grit out of the machine and the cards.
And if you have the time and the patience than get the whole rig dismantled, clean it up well, do the needful with the thermal pastes and heat sinks.
And check all the vents in the Cabinet, make sure all fans are dust free and working.
There is no other reason for a system to heat up so much unless you're stuck in the Sahara at 12 noon........
By the way, where are you geographically located?