Question Quietest PWM pump in idle? Water cooling 3090 RTX - first time water cooling


Mar 16, 2013
Doing my first water cooling mod after finally getting 3090, which is way too loud and too hot compared to my old single fan small form factor gpu.

CPU: i9-9900K
Case: Be Quiet! SILENT BASE 601

Main goal: inaudible in idle mode and fairly quiet when under load. My current setup with low RPM Noctua fans and heatsink makes my PC inaudible in idle or when doing light work and that is what I am used to. I do not want the pump becoming the new loudest component in idle mode.

OC: No plans for overclocking but lets make a little headroom with selected components if it suddenly becomes desirable to push it a bit.

Looking for product recommendations, question answers and thoughts on my findings so far.

  1. Which pump model is most quiet at low flow rate (pwm pump) and which overall (at load)?
  2. 2x AIO’s with 2 pumps (more notable noise sources in idle) vs. single custom loop with 1 pump vs. AIO for GPU only that can be expanded later to add CPU (saw some older EKWB review on this site that could do that)?
  3. If I go with water CPU cooler as well, what do I do with the MB cooling? Will the rest of case fans suffice? Do I need some other cooling components?
  4. If I would cool only GPU, I would want the pump to completely turn off in idle, which would solve the idle pump noise levels. Any pump that does that and is that even good for the loop to be turned off completely?
  5. Is there anything better than distilled water for the loop? Something that would not short circuit components in case of leakage?
  6. With a single loop that includes CPU and GPU, how do I control the pump flow rate? I would imagine it has to be by either CPU fan connector or GPU fan connector because each of those on its own could suddenly ask for more cooling.
What I learned so far: I need a PWM pump, probably a D5, thick radiators with low FPI count.

I would feel much more comfortable with whatever I select if I knew the dB numbers for pumps, especially in idle. At load, fans will probably be louder anyways, as are now with my silent air-cooled PC.

Max dB specification for pump at max load is of little use to me because I know it will be very audible.
Last edited: