This seems weird to me. The r9 295x2 is a 450W card cooled by a 120mm radiator. 120*120=14400 which is only slightly more than 80*80*2=12800.
Radiator surface area I don't think is the problem. The problem is with airflow over the fins. The 80 mm fans can't move enough air over the fins without sounding like a jet engine. To check to be sure the case design wasn't an issue I removed the side panels basically making it an open air test bench and temps only decreased by about 1-2c.
Plus I believe my current water loop has severely limited flow due to the tube routing and reducers. I hope to test this theory Wednesday when I redo the loop in 1/4 tubing. I'm going to give it one more shot with both the CPU and GPU and then I'll likely move to a CPU only loop if the tests don't fair well.
I don't think airflow over the fins is the problem. If you compare the airflow of the best noctua 120mm fan (non-industrial) vs two of the best noctua 80mm fans, the airflow is nearly identical.
It will be interesting to see the temperature with the improved tubing.
Edit: Is that a wrap around bezel in the new design?
Was this printed in nylon or polyamide? They have super high heat resistance
Im seeing 163 c/325 f on the data sheet....
are we lookin at the same thing?
The test with 1/4" tubing in prototype one was unfortunately a failure as I simply could not bleed the system. So moving forward, prototype 2 will be getting larger in order to support off the shelf AIOs and off the shelf pump/res combos. The idea right now is to shrink the footprint to a square with dimensions around the 230mm mark and have a thickness of about 140-150mm and have a max volume under the 8L mark. This will allow the GPU to be traditionally mounted in the case and would not require a GPU riser. The increase in thickness also allows for 92mm AIO support and possibly 120mm AIO support. The increase thickness also allows for standard height CPU air coolers and coolers up to 120mm tall (more or less). I want to target a volume of around 6.7L but it could go as high as 7.5L depending on what I find during the design process.
Might sound silly but what was your loop order? What was the highest/lowest point in the loop?
So no more sub 5L?
Could you try doing sub 7L?
Id be fine with a 6-7L design if it allows for better compatibility, but I'm not very comfortable with an 8L case.
And is the prototype design above a no-go as well? You said it was ~5.3L and that seemed like an optimal design IMO.