That's really disappointing tbh. What about the temps?
I did a test after assembly, it seems to work quite well in my custom DAN A4. I had not previously tested, so I can't make a comparison.
You find the result here:
Nice results, are you using 120mm fan mounted under?
The fans are 100mm and 92mm, larger than ~ 105mm is not possible. They are mounted like that:
The board and the back of the graphics card has a permanent airflow with the fans sucking air in the case. The CPU fan is feeded by air from backside and blows the air through the cooler out of the case, which sounds like a good idea for airflow to me.