Hi all, so I was suspicious my G751 JY (which I've owned 3.5 years) was thermal throttling during gaming, given CPU temp were right up there at 95C.
I downloaded Aida64 free trial (I'd discovered that's what youtuber Linus uses on Linus Tech Tips) and ran the system stability test CPU+FPU+GPU. This revealed 15-20% thermal throttling after about 3 minutes.
Note the cpu (4710HQ) throttles at 95C if you want to use CPUID to determine if throttling occurs. If it hits 95C you are certainly thermal throttling.
I never saw the GPU throttle despite hitting mid 80's. The computer downclocking the cpu regulates the shared heatsink sufficiently that the gpu never needed throttling.
Curious to see if the laptop also throttled in real world application, I kept the stability test window open (not running) to simply monitor while running COD WW2 (maxed settings) and found the CPU throttled to 25% mid game, on the first online match. That's within about 5 minutes.
After further experimenting I found COD WW2 actually caused my computer to throttle harder than Aida64, so that was surprising.
I did some research and found repasting the thermal compound between cpu, gpu and heatsink was a thing people did to help deal with thermal throttling. After watching some disassembly videos, and seeing how fiddly it was, I was put off, but the thought kept bugging me. I was curious to try it out as a bit of a challenge more than actually caring about the thermal throttling. So after a few weeks I decided to go for it and bought some Thermal Grizzly Kryonaut (1 gram) thermal paste and isopropyl alcohol for cleaning the old paste off.
Disasembly was a bit fiddly, but there are youtube vids detailing the process, so no problem other than time consuming.
https://www.youtube.com/results?search_query=g751+repasteThere is thermal paste covering several chips around the cpu and heatsink, so I was nervous my 1gram thermal paste wouldn't cover it all. I needn't have worried as I finished with some left over.
End result - zero thermal throttling after running Aida64 for 20 minutes and COD WW2 for some hours!
Not much different in idle temps - CPU 40-46C idle, GPU 35-43C idle. Fans 2300rpm.
Load temps on cpu are now 89C top and mid 70's on GPU.
Under load CPU now maxes at 89C at which point the fans are around 2800-2900rpm mark with a good 300-400rpm left in them. So at the 89C point the fans now knock the temp down a few degrees everytime the cpu hits 89C. The fans can know maintain a temp ceiling. Whereas before the fans were maxed and the only cooling was to thermal throttle.
So I'm more than happy to now not be thermal throttling at all. Success.
fyi, there wasn't much dust in the laptop which I put down to not having an obvious air intake. Basically air is sucked in around ports and small gaps. Fairly dust resistant.