And a bigger fan and heatsink. There is still loads of room in the chassis.
Is there...? M2 Pro Mac mini on the left...
For further comparison, a picture from the 'original' progenitor. The 2018 Mini (Intel)
The future is now! Apple’s once-neglected Mac mini is coming in hot with a brand new, cutting edge, long awaited … processor upgrade? And a couple...
www.ifixit.com
The part that is a problem is the conjunction in "A bigger fan and a bigger heatsink.". The horizontal 'bar' where the fan casing meets the heat sink is different on the M2 Pro.
The first couple of times I had looked at the M2 Pro Mini thermal set up I thought they had merely just shifted the same fan farther away from the back edge ( and more to the front). But going back to the 2018 and reports of "same speed but louder" there is a subtle difference in the fan. Right where the 'round-ish' part comes back into the 'bottom' (in view orientation above) there is a subtle triangle in the plastic enclosure. That notch isn't there on the M2 Pro's fan. The diameter of the actual rotating fan seems to be a bit less. So technically looks like actual blower on the M2 Pro is smaller than the original fan. [ being 'painted into a corner' because running close up against the front of the enclosure. ] . That is driven by the larger heatsink and larger logical board on the Pro.
On the 2018 the fan sits on top of some logicboard elements. On the M1/M2 Pro them seem to want to drop the fan below the logicboard level. ( the M2 Pro board as a mini 'fan cutout' somewhat similar to the laptop logicboard fan cut outs
MacStadium's Brian Stucki gives a first look at (and teardown of) the Mac mini with M2 Pro.
www.macstadium.com
So the blower has a subtlety smaller diameter, but possibly could be 'taller' to compensate for the loss in diameter. But not the same fan. And probably not the exact same blade design.
If Apple did the "didn't sleep though thermodynamics class" thing it should be a bit taller fan. Hence the cut out. Otherwise have a smaller diameter fan trying to blow more heat out of the box.
).
The M2 Pro package is bigger than the M2 or M1. So the heatsink is going to minimally bigger even if the aggregate thermal output didn't go up.
On the Intel Mac they put the CPU off in the corner and used heat pipes to 'move' the heat over to where they could directly blow it out of the box. The Intel I/O hub (PCH) chip and T2 were more central because that is what the ports actually connect to. (except thunderbolt but those TB controllers are even closer to the ports ).
The catch-22 with "everything in the SoC" means the 'sources' for those ports ( PCIe , USB, Thunderbolt , Display , etc) will 'pull' the main processor out of the corner and into a position near center , but skewed toward the back edge ports.
The Intel model was putting more heat into a smaller heat sink. M2 Pro has a bigger one. The air throughput probably isn't bigger at low rpms though. The output vent is the same. So when need high transfer (and high volume of air ) still pushing lots of mass through a limited sized hole. (which tends to create noise). The M2 Pro is putting a lower "thermal tax" on this set up than the 6 core i7 Intel models were though.
Back to the 2018 logic board. Yes it suck up every last drop of space out to the rounded corner.
[ same iFixit link above for the image source. ]
But the placement trade-offs were different. Apple is pretty much out of room with the larger heat sink shifting the fan's placement. The only claw-back of space that could be made would be to move the power supply. ( which effectively they did with the Studio case.)
If Apple wanted to do a "Princess and the pea" , hyper quiet Mac they could through a Mx Pro into the Studio with a tweak on the power supply. I highly doubt that is a huge market though. I'm sure at some point someone will come out with some 'wrapper' box with a vent output damping buffer on it that cures this hyper queit problem without Apple having to create another SKU model.
P.S. Pretty likely that MacStadium is going to loose about zero sleep over the noise output of these M2 Pro Mini's.