[SOLVED] How could replacing thermal paste and thermal pads decrease heat generated?

Jun 1, 2021
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My buddy replaced his thermal paste and thermal pads on his 3090 and claims it produces less heat now. I just can not figure it out. Everything I know about thermal dynamics tells me it should be producing approximately the same amount of heat (assuming it was not throttling) or more heat (assuming it was throttling).

He is reporting 30-40 degree lower temps which is telling me he is putting more heat into the radiator and he is reporting better 3D mark scores.

He claims the fans are running slower which makes sense as the temps are lower meaning more heat is getting to the radiator but the radiator needs to be hotter to transfer the same amount of heat to the air at a lower speed.

He claims the radiator used to burn to touch but now is only warm to touch. He also reports his room heats up less after the replacement.

I know resistance goes up with temp but the difference from 70 C to 100 C is less then 5% I thought.

I am thinking this is just his preconceived bias but I would love to hear your thoughts.

-edit
All temps were in C
His memory temps were 109 before and 72ish after
VRMs were 95ish and down to 65ish after
T junction was 112 and down to 95
GPU average temp was 92 and down to 84 but he has a hot spot that is up 2 degrees (he suspects bad thermal paste application)

Now the question is did I mark best answer because that is what I wanted to hear lol
 
Last edited:

Karadjgne

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Watts are watts, and the gpu is going to use the same amount, unless throttled. If his 3090 was putting out 300w prior to pad & paste, it's putting out 300w after pad & paste.

So heat output is not going to change, and has nothing to do with the gpu temp. What does affect gpu temp is the efficiency of thermal transfer, if the old pads and paste were sub-par, you get lower efficiency, gpu temps are higher for the same power output.

His fans are temp regulated. With the new pads & paste, he increased thermal transfer, which drops temps on the gpu, which spins the fans slower according to the curve.

That still doesn't affect the amount of heat generated by the gpu, only the amount of heat maintenance required by the gpu.

Only way to actually lower heat output is lower the workload, which lowers power consumption.

Your buddy is suffering from placebo affect. The heatsink is still dealing with the exact same 300w, but prior to pad & paste, the fans were on high and blowing exhaust hard. Now they are slowed down, the fans have less static pressure, so buddy doesn't 'feel' the same amount of hot air movement. Even though it's the same 300w. Turn the fan speeds back to prior use, he'd feel the same heat output, but gpu temps will drop farther.
 

Phaaze88

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It's the same amount of heat... actually, it MIGHT be a little higher, because of Gpu Boost.
The cooler the gpu core runs, the higher the sustained boost clocks are under loads - excluding power limits - and the higher the power consumption.
The memory is going to be the same regardless, because those settings are fixed from the factory and frequency is the only thing that can be controlled by the user.
 
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My buddy replaced his thermal paste and thermal pads on his 3090 and claims it produces less heat now. I just can not figure it out. Everything I know about thermal dynamics tells me it should be producing approximately the same amount of heat (assuming it was not throttling) or more heat (assuming it was throttling).

He is reporting 30-40 degree lower temps which is telling me he is putting more heat into the radiator and he is reporting better 3D mark scores.

He claims the fans are running slower which makes sense as the temps are lower meaning more heat is getting to the radiator but the radiator needs to be hotter to transfer the same amount of heat to the air at a lower speed.

He claims the radiator used to burn to touch but now is only warm to touch. He also reports his room heats up less after the replacement.

I know resistance goes up with temp but the difference from 70 C to 100 C is less then 5% I thought.

I am thinking this is just his preconceived bias but I would love to hear your thoughts.
Your gut instinct is right: the card is producing the same amount of heat. All replacing thermal paste and pads may do is help that heat transfer more efficiently. However, the other things don't make sense, though this is assuming everything was installed properly to begin with. I could see a decrease in GPU temperature after a TIM replacement by way of the cooling system not being properly installed before the replacement and now it's properly installed. However, this wouldn't explain how the radiator suddenly went from "burning" to "not burning" or the room not heating up as much.

If anything, a GPU that's hitting 100C constantly should be using less power overall due to thermal throttling.
 

animekenji

Distinguished
Dec 31, 2010
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It helps disperse the heat better. Diagnostic tools might report a few degrees difference, but 30-40 degrees, regardless of whether it's F or C, is too much to be believed.
 

Karadjgne

Titan
Ambassador
Watts are watts, and the gpu is going to use the same amount, unless throttled. If his 3090 was putting out 300w prior to pad & paste, it's putting out 300w after pad & paste.

So heat output is not going to change, and has nothing to do with the gpu temp. What does affect gpu temp is the efficiency of thermal transfer, if the old pads and paste were sub-par, you get lower efficiency, gpu temps are higher for the same power output.

His fans are temp regulated. With the new pads & paste, he increased thermal transfer, which drops temps on the gpu, which spins the fans slower according to the curve.

That still doesn't affect the amount of heat generated by the gpu, only the amount of heat maintenance required by the gpu.

Only way to actually lower heat output is lower the workload, which lowers power consumption.

Your buddy is suffering from placebo affect. The heatsink is still dealing with the exact same 300w, but prior to pad & paste, the fans were on high and blowing exhaust hard. Now they are slowed down, the fans have less static pressure, so buddy doesn't 'feel' the same amount of hot air movement. Even though it's the same 300w. Turn the fan speeds back to prior use, he'd feel the same heat output, but gpu temps will drop farther.
 

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