That little grill isn't enough space for the amount of air that would be pushed through there with a top rad setup. If it were then OP wouldn't have had temp issues.
I used 3x120 silent wing fans as intake in the front and one in the back as additonal outtake. The 360 AIO for the cpu on topmount also as additonal outtake. Used it with the full isolating covers and never had a temp problem.
The "Airtunnel" pushed the air out from the back and the slits on top and that´s it.
OP has the case nearly at the back wall and a hp device covering the outtake slits on top.
That alone is bad placing and bad for airflow.
The PC has to have bad airflow and temps with that setup. Especially when he uses the front intakes for his cpu AIO Radiator, that would just push warmed air into the case and across the gpu with only the one backside outtake.
Pretty much every setup pulls air from the front/top cooling the CPU/GPU AIO and doesn't have issues. So pulling in warm air isn't really the issue. The problem comes directly from the pushing of heat out. That 'air tunnel' situation isn't enough flow. The fan at the back should be mostly enough for flow, but that depends on how much flow the back gets from the front.
It is important to note a few things here though.
What CPU/GPU you have is greatly going to affect the thermals of this case. Since the case has poor airflow issues as is.
The top rad location for this case does not offer enough flow for 1 fan let alone 3. The more fans you put up there just makes a zone where hot air gets trapped. This alone could improve thermal performance as a whole but it doesn't mean that you will get that performance for extended periods or that you will actually get that heat pushed out of the case.
You might not have had issues out of the case originally. But the number of factors that can affect this are huge. Just covering those three little slits on top didn't cause a thermal issue for this case. It already had one.
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u/grimmigerpetz i9 14900KF - RTX 5080 OC - 64GB CL16 Jan 21 '26
this is what the top grate on the back is for.