120mm AIO in Lian Li PC-Q21

dedocuk · 12 May 2018 at 15:32

Looking at an 8700K build in this case for processing not games, so don't need a graphics card. Need to keep noise down (PC is a couple of feet away from me on desktop) so am looking at mounting a 120mm AIO water cooler at the bottom of the case.

Performance and low noise are #1 priorities, so am looking at Alphacool Eisbaer LT120, maybe with with fan replaced by Noctua NF-A12x25 PWM -- both pump and fan will be PWM controlled from motherboard, would normally be running at ~7V to minimise noise. Reason for Alphacool is that pump can be run at lower voltage to keep noise down, unlike most AIO.

Does anyone have experience of the pump noise from the Alphacool LT, especially at low voltage?

LuckyBenski · 12 May 2018 at 19:36

Are you mixing up PWM speed control and pulse width modulated voltage control?

dedocuk · 12 May 2018 at 23:54

LuckyBenski said:
Are you mixing up PWM speed control and pulse width modulated voltage control?

Not really, the only difference is whether the MB PWM controller sets the voltage (e.g. 7V) and the fan runs at whatever speed that voltage makes it run at, or whether it sets whatever voltage is needed to get the requested speed (e.g. 700rpm) -- the effect is the same in both cases. Not sure whether the LT120 pump feeds back rpm or whether you just set a voltage, either way it should work.

LuckyBenski · 13 May 2018 at 00:34

I don't know any software (or hardware) that lets you set a target speed. You can set a PWM duty cycle in percent, and either you're controlling the PWM control signal or you're directly modulating the supply voltage. Both are hardware implementations but they are different.

LePhuronn · 13 May 2018 at 17:56

You don't want to mess with an AIO's pump speed either. Just plug it in and let PWM control the fans. Unless you have a broken AIO you won't hear the pump.

And at the risk of opening a can of worms here, if you're "processing", not gaming, then why go 8700K? You'd probably be better off with a Ryzen 2700X. What are you "processing" exactly?

dedocuk · 14 May 2018 at 17:08

LePhuronn said:
You don't want to mess with an AIO's pump speed either. Just plug it in and let PWM control the fans. Unless you have a broken AIO you won't hear the pump.

And at the risk of opening a can of worms here, if you're "processing", not gaming, then why go 8700K? You'd probably be better off with a Ryzen 2700X. What are you "processing" exactly?

The Alphacool pump is designed to be run at lower voltages down to 7V to reduce noise is necessary. Processing will be mainly audio (DAW), I could use a Ryzen 2700X but then I'd need a graphics card, which in the Q-21 means no room to fit the AIO cooler, which means a low-profile air cooler (less than 60mm), which means more noise and poorer cooling -- might be able to get a Big Shuriken 2 in but it's 57mm high and clearance is 60mm so it would almost touch the PSU.