I7 5820K operates at 4.2GHz with adaptive 1.25 core voltage and automatic crashing.
I7 5820K operates at 4.2GHz with adaptive 1.25 core voltage and automatic crashing.
I'm not entirely clear on why those 140mm fans were replaced. I'd keep them in place and you're fine with the HDD rack. Just take out the second HDD rack if you don't need it, as that would improve airflow.
The problem with the 750D versus the 750D airflow version is that the front fans struggle to draw in air from outside due to the case's front panel design. Strong fans at the top should help supply air efficiently, and with good 140mm fans they should run quietly even at high speeds.
Don't reverse those top fans in your setup. That would just force more air into the case without letting warm air escape properly. You need better airflow directed toward the GPU.
If possible, install a 120mm fan on the left side of the HDD cage and aim it directly at the GPU. You'll likely need to secure it with zip ties or similar, but this should help push more air into the system from your front fans.
I'm not entirely clear on why those 140mm fans were replaced. I'd be fine leaving them in place, and using the HDD rack is perfectly acceptable. Just take out the second HDD rack if you don't need it, as that would improve airflow.
The problem with the 750D versus the 750D Airflow edition lies in the front fans' ability to draw air from outside due to the case's front panel design. Strong fans up there should help supply air even at high RPMs, and with good 140mm fans they should remain relatively quiet.
Don't invert those top fans in your setup. That would only force more air into the case without letting warm air escape properly. You really need to increase airflow directed to the GPU.
If possible, consider installing a 120mm fan on the left side of the HDD cage and pointing it straight at your GPU. You'll likely need to secure it with zip ties or similar, but this should improve air delivery from the front fans.
I ended up moving my GPU into a PCIE slot because I initially placed it in the second slot without realizing it caused 62°C temperatures. It's fixed now. Also, IO supports the 750D Airflow, and thank you for your assistance—your help was valuable even though I resolved it with another method.