Happy new year! First off, some good news 
I have data that confirms there has been none to a negligible drop in performance of my PTM7950 application after ~17 months of continuous use.
I finally got around to this, and swapped my Intel i7-1165G7 board back in to retest. The board with PTM7950 has been in use from ~July 2022 to early November 2023, so well over a year. Initially, I thought I had cleaned out all the dust (there was a lot), ran all the tests in my original post again, and was seeing over ~5C hotter temps (10C at the extreme, at high power). I was puzzled, and thought my PTM7950 application had degraded. Then, I rechecked by partially taking off the fan cover, and lo and behold there was more dust. I cleaned that off, reran the tests, and temps were back to how they were originally!
The area in the green boxes [a] are easy to see and clean dust from. However, the area in the red box [b] is hard to get to and clean:
And I did not want to remove the entire heatsink for the risk of damaging my precious PTM7950 application. So to avoid that, I took out the entire mainboard, unscrewed these 2 screws (yellow boxes [s]) on the front side:
as well as these 3 screws (yellow boxes [s]) on the back side. Afterwards, the area in the blue box [bmc] is still attached to the heatsink via a bent metal clasp? which didn’t look like it could be easily undone without breaking:
I kept the rest of the heatsink assembly screwed in/attached to the mainboard.
Finally, with all those screws undone, the fan can be gently pushed out enough so that the bottom of that hard to reach area (red box [b]) is revealed:
If you zoom in, you can see that there’s dust blocking the fins and yes, it doesn’t look like much. But little amount was causing an increase of 5-10C! I had already removed a ton of dust from the green boxes, so my temps must’ve been even much higher. I definitely noticed an increase in fan load/noise during regular usage (but let it be), and am confident it was the dust. Now I wonder if the increased fan load led to a decrease in battery life because:
After I cleaned that area (very easy to do with a cotton swab and some alcohol, or carefully with water) and reassembled, temps dropped back to how they originally were on day 1 PMT7950. Yay!
For brevity, here’s the previous stress-ng test on July 2022 (room thermostat said 73)
compared to more than 19 months later on December 2023 (room thermostat said 71F FWIW):
With only the green boxes cleaned and not the red box (not fully cleaned):
CPU temps were ~82C, so ~6C hotter.
After the red box was cleaned so that the fans and heatsink are fully cleaned:
CPU temps went back down to ~77C, so ~1C hotter (probably within the margin of error).
Regarding my AMD 7840U upgrade, I’ve been using the board since early November and have ran it through a gamut of tasks. The fans rarely (almost never) spin up during lighter tasks like web browsing, video watching, and programming work, at least in Fedora. I tried gaming for a bit, and they ran surprisingly to shockingly well (especially with AMD FSR upscaling to a 3440x1440@60Hz monitor; it’s a gamechanger, pun intended. I consider 60FPS+ “playable”). I tried Halo Infinite multiplayer (big team battle), Ghostrunner 1 (played through the entire game) and 2, Switch emulation. Anyways, less about gaming performance and more about temps: it looked like temps were capping at ~80C GPU and a bit less on CPU. Fans were max, and fairly loud but not annoying and the chassis got hot, but never uncomfortably hot to use. I’m also wary of a hot chassis that would degrade battery longevity. Gaming on just the built-in keyboard and external mouse was totally fine!
Interestingly, if I set RADEON_POWER_PROFILE_ON_AC=high it will keep the GPU clocked to 2800Mhz and the GPU temperature will steadily rise to 104C in Halo Infinite and then the system will instantly shut off (likely because of some thermal limit safety feature).
This is to say that the stock 7840U thermals are I’d say is very good already. However, I noticed that if I ran e.g. 3DMark Time Spy with the top input cover off, I’d get about 100 more points, so at least on my system, there’s room for improvement. I was only able to reach the same score (3150-3160) as here with the cover off.
^ I think it was! With my input cover on (so regular laptop use), I was only getting a score of ~3050. Not a big difference, but it shows there’s room for improvement from stock.
Now that I have a good idea of how that performs, I’ll be switching to PTM7950 (a huge thanks again to those that posted their results) — I’m confident that the temps will be even better and may allow some more performance out of the machine.
Unfortunately, I’ll have to wait before I make any modifications due to this issue I’m experiencing. I don’t want to add any confounding variables or warranty troubles for Framework support.
@VeryRoomy / @Adrian_Joachim wrt power limits, this is apparently where it’s set in the EC if I’m understanding correctly. Referencing it here with a here be dragons and all the appropriate warnings with messing with that