Build rework!
I have found a new configuration I'm enjoying. Case, CPU, and mobo still the same. I'm using a Thermalright SI -100 x Noctua NF-A9x14 and a 92mm to 120mm Fan Adapter Offset. I have the fan with the 92mm fan to 120mm fan offset adapter (I printed out of PETG) between the cpu cooler baseplate and the beginning of the finstack. ((Depending on your ram it might be a little tricky. If you're mobo doesn't have huge VRM heatsink like mine, you can easily use a Noctua NF-A12x15 and point the overhanging part of the cooler away from the ram.))
Because of this configuration I was able to increase my PL1 & PL2 to base line specs and didn't break 84°C via Cinebench. The cpu also cools down faster. I'll admit my biggest issue was mounting the adapter to the finstack but the included fan wire brackets made it really simple as well as zip ties. Now I have a well cooled ~ 15L sff build with a 14700k, 5090 FE and full sized mobo. I'm surprised it was possible.
Link to the adapter: https://www.thingiverse.com/thing:3060068
I tried the big 140mm Noctua fan and low profile cooler and this is what I learned:
Alrighty. I hope I can answer some questions other's might have with the 140mm Noctua fan mod and low profile cooler of your choice that'll fit your sff case cpu cooler max height.
I'm currently using a 14700k: PL1-125W PL2-188W. The case I'm using is the SSUPD Meshroom S V2 with an ATX board, the Asus Z690 Formula Maximus, to be exact. It also has a 77mm clearance but I think you can get away with 79-80mm tops.
The NF-A14x25r G2 worked with both the Scythe Big Shuriken 4 and the PCCOOLER RC600-67. For the BS4 I was able to use the longer 25mm screws to attach the fan just like the ID-cooling from the Terra case video. For the RC600 I found some spare 25mm fan wire brackets and was able to secure NF-A14x25r securely onto the heatsink without any real issue.
Results: I didn't see that much more improvement in my CPU temps, they actually climbed a bit. Both coolers put the max temp as high as 86~92°C under full Cinebench 10 min load. Before the NF-A14x25r mod, my temps where 86°C highest on both coolers with their stock 15mm fans.
Although, the 140mm fan does move more air it capped at 1500rpm. The slim orginal fans that came with these coolers are 1800rpms + and thus why I think the temperature was lower. Now I would like to mention that my RAM benefited a 7°C drop due to more air reaching the dimms.
I for one enjoy this type of parts exploration, especially with SFF builds.