heat dissipation on cpu vs gpu

[VeganJoy]

not sure if this was supposed to be in the gpu section, sorry!

 

so i recently came into possession of a 980ti, and after much troubleshooting it seems that the original fans don't work. so i ziptied the stock case fans that came with my meshify onto the radiator and set them to max speed (1200 rpm) and it appears to work fine. despite this crazy mofo of a card pulling 360 watts it won't go over 76C in furmark.

 

in comparison, i have a d15s on my 9700k and for testing purposes i put an extra corsair ml120 on the intake end at full speed (2000 rpm) and tested my overclock in p95. 4.8 ghz with avx on pulls 200-220 watts and gets above 95C before i get worried and stop it.

 

so how can the 980ti cool itself so much better than my cpu? im using TG kryonaut on both but even if i were to delid the 9700k and use LM with a direct die frame i wouldn't expect to drop my temps by 20C and it's pulling 2/3rds the wattage. i've got an evga 1080ti ftw3 coming in today or tomorrow which i'll be testing, iirc it has a hard limit of 250w so i wonder if it'll run much cooler than the 980ti. for reference the 980ti is a gigabyte xtreme windforce, which appears to have two 120mm radiators with those oversized 12mm heat pipes.

[Hairless Monkey]

Couple things. First, the 980ti has a much larger die, so the heat is spread out more. Second, the CPU has several extra layers of heat transfer because of the IHS (integrated heat spreader). For the 980ti it's die->thermal ccompound->cooler->Air where-as for the CPU it is Die->thermal compound->IHS->thermal compound->cooler->Air. Finally the die on the 980ti isn't consuming all of that power, the memory and VRM efficiency also have to be accounted for.

[VeganJoy]

4 minutes ago, HairlessMonkeyBoy said:

Couple things. First, the 980ti has a much larger die, so the heat is spread out more. Second, the CPU has several extra layers of heat transfer because of the IHS (integrated heat spreader). For the 980ti it's die->thermal ccompound->cooler->Air where-as for the CPU it is Die->thermal compound->IHS->thermal compound->cooler->Air. Finally the die on the 980ti isn't consuming all of that power, the memory and VRM efficiency also have to be accounted for.

looking at gpu-z the chip is pulling 300w (dunno about vrm losses) and the memory is pulling 60w. how about with other gpus? i know that a lot of navi cards run really hot, my buddy's 5700xt's junction temps are over 90C and that card doesnt use over 220w afaik

[Demonic Donut]

50 minutes ago, VeganJoy said:

looking at gpu-z the chip is pulling 300w (dunno about vrm losses) and the memory is pulling 60w. how about with other gpus? i know that a lot of navi cards run really hot, my buddy's 5700xt's junction temps are over 90C and that card doesnt use over 220w afaik

It's all cooler design and die density. I just upgraded my 5700xt cooler + liquid metal recently and dropped temps a ton.

 

Delid and liquid metal would help your CPU a lot. Also, prime95 is not a realistic load. Fine for stress test and stability, but you'll never see that in actual use. Unless you are using prime95 for it's intended purpose every day.

 

You are overclocking, and probably increasing voltage, and then hitting it with the hardest load you can. Its going to get HOT when you run it outside of design parameters. Temp (wattage of chip) increase is not linear with voltage and clocks, it's an exponential curve.

 

Overclocking isn't just about finding stability at the highest clocks, it's about managing heat too. And often that's the limiting factor.

[VeganJoy]

oh yeah i'm aware of all that. i run half the cores on PRPs 24/7 cause they recently made it self checking so it's great for memtesting which i've been doing a lot of. i prefer to push my hardware with an "unrealistic" load as i dont want any stability issues. could do 5.1ghz for games without too much heat but it wouldnt handle p95 well. i wouldnt wanna run a system thats only stable if youre not utilizing its full power.

[VeganJoy]

5 minutes ago, Demonic Donut said:

It's all cooler design and die density. I just upgraded my 5700xt cooler + liquid metal recently and dropped temps a ton.

 

Delid and liquid metal would help your CPU a lot. Also, prime95 is not a realistic load. Fine for stress test and stability, but you'll never see that in actual use. Unless you are using prime95 for it's intended purpose every day.

 

You are overclocking, and probably increasing voltage, and then hitting it with the hardest load you can. Its going to get HOT when you run it outside of design parameters. Temp (wattage of chip) increase is not linear with voltage and clocks, it's an exponential curve.

 

Overclocking isn't just about finding stability at the highest clocks, it's about managing heat too. And often that's the limiting factor.

mb forgot to tag you

[Demonic Donut]

6 minutes ago, VeganJoy said:

oh yeah i'm aware of all that. i run half the cores on PRPs 24/7 cause they recently made it self checking so it's great for memtesting which i've been doing a lot of. i prefer to push my hardware with an "unrealistic" load as i dont want any stability issues. could do 5.1ghz for games without too much heat but it wouldnt handle p95 well. i wouldnt wanna run a system thats only stable if youre not utilizing its full power.

Are you having memory issues or working a new RAM OC? Why test constantly?

 

I understand wanting to be stable, you are just at the limits of your hardware, heat wise, with the work you are doing.

 

Back to the original post though, it's normal for CPUs to be hotter than GPUs with equivalent power draw for all of the reasons @hairlessmonkeyboy said.

[VeganJoy]

1 hour ago, Demonic Donut said:

Are you having memory issues or working a new RAM OC? Why test constantly?

 

I understand wanting to be stable, you are just at the limits of your hardware, heat wise, with the work you are doing.

 

Back to the original post though, it's normal for CPUs to be hotter than GPUs with equivalent power draw for all of the reasons @hairlessmonkeyboy said.

been building a new system for a few weeks now and i've been working on OCs for several different kits. i also just contribute to GIMPS regularly.