Recently completed a build with this chassis.
A quick thermal observation after running a GPU benchmark on a blower style eVGA 1070 all day:
I found that the large 200MM fan has the odd effect of increasing GPU temps! That's right, running the 200MM fan actually increases GPU temps by 5-6C. I've tried switching the perforated panel on the right side (near the SDD/HDD cages) to the top, but this only improved things by about 1-1.5C.
My fluid dynamics theory is that heat "pools" and is trapped just under the top left bracket with nowhere to go. The front 200MM fan actually pushes this heat further into the corner, giving it less chance to dissipate. Shutting the fan off removes this positive differential allowing that circulating hot air just above the GPU heat sink to bleed off into the case. I found the GPU to hover in the 78C range with front 200mm fan on, and 72C with fan off.
Now, the solution is NOT to turn the 200MM off - other components significantly heat up when this is off. CPU and PCH climbed about 8-10C with the 200MM off. It's not a good situation.
Thermaltake has some work to improve this case for blower-style GPUs like mine. I think a good start would be to significantly perforate the sheet metal at the top left corner and into the acrylic window. Reduce the size of the acrylic window if necessary. I may try a mod, but I'm afraid of butchering the case, and the problem won't be solved by just putting a few dozen holes in the top panel. The overall chassis needs better ventilation above the GPU side of the case.
I should note, I have not yet installed two 80MM exhaust fans - I have a pair coming in on Sunday and I will report back if this significantly helps. You may say "duh bro, you need input and output" - and you might be right. But my goal all along has been to reduce fans to keep the whole setup as quiet as possible. Running this GPU under load in the upper 70s isn't terrible, but I would prefer it run cooler and quieter for better OC headroom.