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|
|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.