There's no shortage of cooling capacity in my system, so the real question is how quiet I want it to be, and what thermal limits it needs to keep within.
Based on some reeeally vagues ideas from an Optimum Tech video, a GPU temp of ~60°C is okay for a gaming load, with CPU around 55°C.
Under a pure CPU workload he's showing temps in mid 70s as okay, but that's a 12700K that has a much larger power envelope - about 140W for my 5800X vs 190W for the Intel chip.
That video assumes rad fans around 1000rpm, and pump around 2000 rpm. Because I generally have headphones on, I'm happy to run rads at 1400rpm under load (75% PWM), and the pump is so damn quiet that it doesn't really matter what setting it's on.
| PWM percentage | Fan RPM | Pump RPM | Notes |
| 75% | 1450 | 3925 | Max speed, only when loop temp hits 38°C |
| 66% | 1250 | 3400 | Pump is quieter at 66% than 60% |
| 60% | 1180 | 3080 | Pump resonates, noise is just noticeable |
| 55% | 1100 | 2800 | |
| 50% | 980 | 2500 | |
| 40% | 780 | 1950 | Idle speed, stays here while loop temp below 28°C |
I'm pretty sure I could safely pull the top of the curve right down, I don't think there's much drop in coolant temp by running the fans beyond 1250rpm. I need to do some heavy gaming and see how bad the temps get, just find what temperature the coolant stabilises at for a given CPU and GPU temperature.