If you are using zinc-based white thermal compound on bare die stuff, that's pathetic paste to use, only 1w/mk, not enough surface area, only good for ceramic large surface cooling like 486 and pentium, and that's about it, high wattage large surface metal top might not be enough. MX-4 is easy to get is around 8w/mk and should have tube of these in your toolkit. For important stuff and must have and little expensive but worth having is 11w/mk is Grizzly Hydrouant. The top of the line is 14w/mk, again from Grizzly's, not the metallic compound.
I get same complaints from stupid people who use chinese paste (grey stuff from that source and anything in between are also 1w/mk) in their Xbox one and PS4 under load, fan spin louder, I can make a console quiet and reliable using Grizzly Hydrouant or MX-4.
59C is hot. Can upset a weak chip, Get 99% alcohol and dribble few drops on the silicon image IC and see if that improves. Evaporating alcohol carries away extra heat causing evaporative cooling effect.
If not enough cooling a chip, if you have a canned air, invert it, that's basically liquid C02, same stuff as freeze spray is, and cheaper! Or air compressor if you have one, shoot a stream of air at the chip, spot cooling it.
I use 99% alcohol to wet a live board in order to find short via looking for boiling component circuit board old technician's trick of tools. Phones when got spilled on of anything that contains water (tea, sea etc, except distilled water, develops short circuits through electrical conductive liquid and corrodes rapidly when on, even low voltage, at metallic terminals of components and some develop short circuit internal (especially multilayer solid capacitor).
I also use alcohol of this type to dry out also to dilute washed board after plain or distrilled water rinse.
Great Northern aka Canada.