Question Why did my GPU start thermal throttling at 80c?


Nov 1, 2017
I have an Acer Nitro 5 laptop with a GTX 1660Ti and an i7 9750H. Yesterday I decided to repaste the CPU and GPU due to increased temps. I used a Cooler Master MasterGel Pro. While cleaning the old paste I noticed that some of it had seeped in between the gpu transistors. It was hard to remove so I didn't bother.

After repasting and putting the laptop back together I did some stress testing on both the CPU and the GPU. CPU was now hitting around 84c down from 94c and GPU was hitting 80c down from 89c. What I didn't realize from the testing was that the GPU was actually never going beyond 80c. I fired up some games and was surprised to notice that after 15-30secs my fps dropped severly from a smooth 70+ fps down to 30+ fps. I fired up MSI Afterburner to monitor the GPU and was surprised to notice that the GPU was severly thermal throttling as soon as it hit 80c. It was like I had somehow managed to cap the thermal limit of the GPU to 80c. After doing some research online I figured it might be improper repasting although I am sure I had done everything correctly. I decided to repaste again. After the 2nd repaste my GPU is now no longer severly throttling at 80c and gives good performance and maxes out at 85c.

What was the reason behind the GPU severly throttling after the first repaste?

A couple of things to consider. First thing I noticed while disassembling the heat sink the 2nd time round was that I had overtightened the screws a little bit. From what I can remember I probably also failed to tighten the screws in a diagonal manner as is common practice with heat sinks in order to allow the thermal paste to spread evenly. On removing the heat sink I found that the thermal paste had failed to reach a small portion of the GPU die.

Before the 2nd repaste I first managed to clean the old thermal paste from in between the GPU transistors with an ear cleaning bud. I also took care while reapplying the heat sink to do so in a diagonal manner and to not overtighten the screws. Was that the issue then? Could overtightening of the heat sink have led to the GPU thermal throttling at 80c? Could improper spreading of the thermal paste have caused it? Could the old thermal paste in between the GPU transistors not being cleaned properly have caused the throttling? Did I somehow cause damage to my GPU? Should I be concerned? The performance so far has been great just like before but with better temps. But I am not sure if this issue could crop up in the future.

PS. I used the pea method thermal paste application. I might have added a little too much during the 1st repaste although I could still see the IHS through the thermal paste on the 2nd attempt so not too bad.
Jun 13, 2020
After first repaste, the paste does not properly spread and that's why heat sink does not properly fitted, and you also not screw diagonally. Because of this reason GPU is not pushing extra and started throttling @ 80C. After heating, it started to push down its performance to Cool down the Chip