They are actually not that much bigger or different from mobile or game console GPUs, they just have a lot of cooling bolted to them. The cooling allows them to sacrifice efficiency, to be more power hungry and more powerful.

It’s a little amusing how many respondents thought mobile GPUs meant laptop GPUs despite it being clear in your post.

There are several factors at play from mobile GPUs being ARM based, having unified memory and some laws of physics meaning more size and power has diminishing returns.

Phone GPUs based are generally comparable to budget desktop GPUs on a per generation comparison.

Despite this mobile games tend to look amazing compared to what you would expect out of a PC game on low end hardware.

Part of this is optimisation, part of it is more efficient graphics libraries targeting a much lower range of hardware. Similar to how lower spec consoles often have great looking games, targeting only one hardware layout can allow for crazy optimisations.

See the PS3 era games for examples of really pushing hardware to its absolute limits for graphics.

Sadly my answer isn’t as technically detailed as Id like but it’s a complex topic when you really delve into it.

I have the largest laptop GPU from the last generation; 3080Ti @ 16GB.

You must have very small fans moving a lot of air in a laptop. That means speed and speed is the primary cause of noise in fans. Larger desktop PC GPUs can have a larger heatmass sink and more/larger fans that run at a slower speed.

Aside from the noise, the laptop has a more complicated set of breakouts and interrupts for thermal and battery management. This means it may have different firmware/software support and issues if you do higher risk types of activities like messing with the clock rate.

One example I can give is when using AI on my laptop with various models I am able to split between CPU and GPU for inference. The thermal performance will impact throttling. I must balance both the workload and the thermals to maximize the inference speed for things like Low Rank Adaptors training where I need to run a model for a long time at near maximum output for my hardware. If there is more load on either, the shared thermal management will throttle sooner. Indeed I wrote a script to monitor the CPU/GPU temps and memory usage every few seconds just to dial in this issue.

Basically, it seems to me like the technology in mobile GPUs is crazier than desktop/laptop GPUs.

It’s not. They have the same software technologies and the desktop counterparts have better hardware.

but not by enough that it seems to need to be 100x bigger than a mobile GPU.

Yes it is. No benchmarks would agree with you here. Also, just look at the power draw for each and how much noise each cooling solution makes.

And top end mobile GPUs actually perform quite admirably when it comes to graphics and power.

Depends entirely on what you see as admirable. Power efficiency wise, they’re great, but their performance isn’t anything to write home about, especially considering that they typically share cooling solutions with the CPU. And that’s at the top of the line. Lower down, it’s not all that great, with desktop counterparts having much better 1% lows when the power is more comparable.

So with most of what you said being incorrect, your conclusion is also incorrect. Generally, more surface area on coolers means they can cool higher power limits, can have bigger fans and/or have those fans spin slower so they’re much quieter. Regarding the power consumption, it’s simply diminishing returns. Mobile GPUs are just cut sooner on the graph.

I just want to add, the Nvidia 4090 mobile gpu is the 4080 desktop chip, but at lower clocks and therefor better power efficiency. However it has much lower performance in comparison to a desktop 4090 and lower than the desktop 4080 as well.

I don’t really see it. Like I expected the iOS Resident Evil 4 remake to perform about the same as the PS4 Version but its way worse.

Cost. It’s always about money.