How is the GPU able to dissipate so many W at the same temp vs the cpu ?

[Quixote]

So I have a Ryzen 3950x on a dark rock pro 4 cooler & an MSI rx 6800 gaming X on the cooling that comes with.

So i was playing Shadow of the Tomb Raider at stupid 4k settings & very nice it is indeed. Meanwhile, I had AMD adrenaline or whatever it's called open out of curiosity. The rx 6800 would generally be at 65-100% usage, depending on the scene, often 90% + - this gave 70 deg GPU temp, 80 deg hotspot when under 95+% load. Power consumption was in the 150w - 200w range.

Meanwhile, the CPU was always around 6% (16 core CPU, Tomb Raider just doesn't require heavy threading). Adrenaline said it was consuming 50-60 watt but the temp was 70 deg ? It wasn't even hitting top single-core clocks, it was around 3.2 ghz.
OK, so I run a CPU benchmark, Cinebench R23 & the all core temp is 75 deg, consuming 103 watt, so it basically has almost the same temp regardless of the utilisation & watts being consumed.

So I have a question:

- Given that the CPU & GPU are both TMSC 7nm (I think ? I could be wrong) - how come the GPU using 4* as much power in W is able to maintain similar temps? Especially given that I have one of the best mainstream air coolers on the cpu ?

- Or to put it another way : Why is the CPU at 70 deg when lightly threaded & not even hitting max clocks ?

& then more of a statement:

It's crazy how we've got to the point where how many cores are being loaded makes basically no difference to CPU temps, where heavy single-core loads at much lower wattages result in basically the same temps, give or take. This is due to how modern CPUs work, but it takes a lot of mental adjustment to get used to.

I suppose what's happening is that the CPU is load balancing the fan to maintain lowest possible noise at steady temps. I'm just amazed how much more Watts the GPU can deal with, without becoming noisy as hell.

 

[Quixote]

Wow, thanks everyone, some very informative answers. I had an inkling as to what it might be about but these replies really clarified things. I should mention, I was playing at a v-synced 60fps which is why the GPu wasn't always at 100% load - it just depended on how demanding the scen was whether it needed to push that hard.

 

[Quixote]

The heatsink on that RX6800 is massive, that is how it manages to dissipate so much energy and remain quiet. I was shocked how much bigger my Asus Tuf 6800 was than my GTX 1080, would say over 2x the fin surface area. Also , for this generation of graphics cards the 6800 is very frugal in its power requirements. 6800 uses less Watts than 3070ti that has similar performance

Yeah, I came from a 1080ti FE & the new card is absolutely massively bigger, even though on paper it consumes less power than the 1080ti (people say the new cards are more 'spiky' than older gens). It's also noticably a lot quieter than the 1080ti, although that was never a problem, it wasn't too loud & it was a nice, whooshy sort of noise that didn't really bother me. I think it's partly because most companies are using the same cooler for their 6800 as their 6800xt, so they are kind of over-engineered for the 6800.

 

[Quixote]

The GPU die itself won't be using all the power as you have other things like the GDDR6 drawing power also.

Good point - I think that's especially true of the NVidia cards with their GDDR6x - although I guess they have less of it, so it might balance out.