I have 2x MasterFan Pro 140 Air Pressure that I purchased for $5 each from Amazon (will have to run them at low RPM ranges after reading about high noise and vibration), 2x 120mm fans that came with the case, 2x 80mm axial fans that I am considering using for the upper frontal air intake on top of the 2x 140mm fans (with a slight overlap), and 4x 80mm blower fans that I am considering using for exhausting below the GPU to improve the airflow across it.
I'm also going to be buying an Arctic F14 Silent or F14 TC and a PWM cable splitter (around $8 after discount). I acquired the 80mm axial and blower fans for free, although a major limitation is that they are USB powered, which will require unconventional wiring to the motherboard's I/O panel to power them.
I'm currently trying to decide between having (intake: 3x 140mm (one on the bottom) and 2x 80mm) and (exhaust: 2x 120mm and 4x 80mm blower)
OR: (intake: 2x 140mm, 1x 120mm on the bottom, and 2x 80mm) and (exhaust: 1x 120mm, 1x140mm and 4x 80mm blower exhausts)
My only concern with the 2nd option is that the 120mm bottom fan's mounting holes would be right next to the non-modular PSU so the cables will be blocking a large chunk of the airflow, while the 140mm bottom fan's mounting holes are spaced further away from the PSU.
The end goal is having all of the fans at slow speed for quiet gaming, and for the case + fans to last for more than one upgrade. My current build will be a Ryzen 1600, Asrock B450M Pro4, 2x8GB 3200 MHz RAM, RX 570, SATA SSD and M.2 SSD. Future upgrade would very likely to be a used Zen 3 CPU and a used later generation GPU on the same mobo, RAM and PSU.
Backup links in case if the embedded images don't work:
https://imgur.com/a/e6EJLHz
https://imgur.com/a/Y5acQVq