G751jy Temperature almost the same after changing thermal paste

[Cannon_19]

I haven't changed the thermal paste in my rog g751jy in 2 years so I did it yesterday. I also cleaned all the dust. Before doing it, while playing Battlefield 1 my gpu was constantly at 86-87 degrees celsius and throttling, while cpu was around 92-97, with clock speeds bouncing between 3GHz and 3.3GHz, also reaching 3.4GHz sometimes. Fan speeds were around 3000rpm for gpu and 3300rpm for the cpu. After I was done with the paste and cleaning, I ran Battlefield 1 again and gpu never went above 75-76 degrees and was always at full speed. CPU however, runs at 3.4GHz all the time, and then it gets to 92 degrees and drops to 2.5GHz and ~83 degrees, and then goes back to 3.4GHz until it's at 92 degrees and it's a never ending cycle. Fan speeds were 3000rpm for the gpu and 3000rpm for the cpu (300rpm less than before for cpu). Idle temperatures are 40 degrees for the gpu and 45 degrees for cpu. Is this a normal result? I'm happy with the gpu results, but underwhelmed with cpu results. It never fell to 2.5GHz before, and why are the fans running 300rpm slower? Did I do something wrong? Any way to fix this? The thermal paste I used was Thermal Grizzly Kryonaut and Arctic thermal pads for the vram and vrm (0.5mm and 1mm). I spread the paste with included spatula, as recommended by thermal grizzly. Is there maybe a curing time for the paste or something?

Here are the pictures:
Before cleaning:



GPU:



After cleaning (I cleaned the vram and vrms too but didn't take a picture):

CPU:



GPU:



New paste and thermal pads:

Thermal pads on the heatsink:



GPU:



CPU:

[andreacos92]

My guess: you shouldn't have used the 1 mm pads over the GPU VRMs. They are too thick to allow the right pressure and contact between CPU and copper CPU heatsink
Maybe even the 0.5 mm could be too thick.

With my latest repaste on G751JY I went with thermal paste everywhere, because even with 0.5 mm pads I noticed higher temperatures on some CPU cores (more than 10°C differences from hottest and coldest core), so I thought that heatsink was not completely "flat" on the CPU die.

[Cannon_19]

andreacos92 wrote:
My guess: you shouldn't have used the 1 mm pads over the GPU VRMs. They are too thick to allow the right pressure and contact between CPU and copper CPU heatsink
Maybe even the 0.5 mm could be too thick.

With my latest repaste on G751JY I went with thermal paste everywhere, because even with 0.5 mm pads I noticed higher temperatures on some CPU cores (more than 10°C differences from hottest and coldest core), so I thought that heatsink was not completely "flat" on the CPU die.

I initially went with 0.5mm for everything, but after I put the heatsink back on, I inspected the thermal pads from the sides with a lamp, and I could clearly see the light coming through between the VRMs and thermal pad, meaning there was no contact between them at all. That's why I went with 1mm for them. Other parts seemed to make contact with 0.5m just fine so I left them like that.
EDIT: Forgot to ask, what temperatures should I normally expect for cpu/gpu after cleaning everything and reapplying the paste?

[andreacos92]

Cannon.19 wrote:
I initially went with 0.5mm for everything, but after I put the heatsink back on, I inspected the thermal pads from the sides with a lamp, and I could clearly see the light coming through between the VRMs and thermal pad, meaning there was no contact between them at all. That's why I went with 1mm for them. Other parts seemed to make contact with 0.5m just fine so I left them like that.
EDIT: Forgot to ask, what temperatures should I normally expect for cpu/gpu after cleaning everything and reapplying the paste?

I know that with 0.5 mm pads or with thermal paste the VRMs are not well in contact with heatsink, but I gave priority to CPU and GPU die contact-pressure-cooling.
Anyway, in my case, using thermal paste over the VRMs resulted in a well spreaded thermal compound: I considered it quite enough.

The fact that other parts make a good contact with 0.5 mm can be seen in a negative way, they are relieving pressure from the chip dies.

About the temperature, I assume you have the 4710HQ or 4720HQ. I don't know exactly because my 4710HQ is undervolted in daily use and overvolted/overclocked when needed, but with stock clocks and voltages you should not touch thermal throttling like you experienced, unless your room temperature is over 30 °C.
Maybe in the middle 80s seems to be plausible and acceptable when playing demanding games.

Right now, with an ambient temperature of 28 °C (it's hot here), my CPU idles at 38-42 °C with a little undervolting (that has little/zero impact on idle temps anyway).

[Cannon_19]

andreacos92 wrote:
I know that with 0.5 mm pads or with thermal paste the VRMs are not well in contact with heatsink, but I gave priority to CPU and GPU die contact-pressure-cooling.
Anyway, in my case, using thermal paste over the VRMs resulted in a well spreaded thermal compound: I considered it quite enough.

The fact that other parts make a good contact with 0.5 mm can be seen in a negative way, they are relieving pressure from the chip dies.

About the temperature, I assume you have the 4710HQ or 4720HQ. I don't know exactly because my 4710HQ is undervolted in daily use and overvolted/overclocked when needed, but with stock clocks and voltages you should not touch thermal throttling like you experienced, unless your room temperature is over 30 °C.
Maybe in the middle 80s seems to be plausible and acceptable when playing demanding games.

Right now, with an ambient temperature of 28 °C (it's hot here), my CPU idles at 38-42 °C with a little undervolting (that has little/zero impact on idle temps anyway).

Yes, I have a 4720HQ. it's not overclocked or undervolted right now. During stress test in Intel XTU, the cpu temperature doesn't go above 82 degrees but it keeps showing "Power limit throttling: yes". Also it doesn't let me undervolt any lower than 0.090. I tried -0.045 yesterday and there was no difference in temperature.