Update: I finally solved it. Following the advice of someone that posted in a Ghost S1 thread to turn the case upside down, my Dan case never gets hot. Now the exhaust from the fans gets shot out from the top instead of rising up from the bottom. The temperature on the surface of the case now feels warm instead of hot. PLUS, my cpu temps while gaming dropped 3 degrees (59 to 56) and gpu temps dropped 5 degrees C (69 to 64). Idle temps reported in Ryzen Master went from 43~45 to 42 ish. I'm very happy with air cooling a 3600 in Dan Case v4.
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I've been tinkering with my Dan A4 to lower the temperature of the top panel after gaming for a while. Build is a 3600 cooled with a L9a and the 3d print fan shroud, two exhaust fans at the bottom of the case, and an EVGA GTX 1070 Gaming SC.
To improve the case temperatures I did the tape mod on the side panels and installed 3 40x20x20mm fans as exhaust on the top of the case. I also taped the top of the 1070 so air flows down into the bottom exhaust fans. This all helped with temperatures a lot (gpu never goes over 69 degrees). However, long term gaming in FFXIV at max settings causes a gradual heating of the top panel. It's not as hot as before, but still hotter than I prefer.
I think the issue is heat from the L9a horizontal fin orientation gets trapped in the case and over time heats the top. My question is: will installing a 645LT with bottom fans as intake (and taping the bottom of the 1070 instead of the top) prevent excess heat from the cpu from heating the top panel as much? Or, since all the hot air is going up, will the top heat up the same or worse? I would do all this to test since I already have a 645LT, but that's a lot of work if anyone else knows the answer already.