Sizing an AIO Cooler

Foef_Yet_Flalf · April 16, 2020

I have an existing AIO water cooler I'd like to carry over in my next build. Unfortunately, I have no way of knowing how well it will operate when posed with a CPU with a higher TDP. I have the spec sheet for the AIO, but of course, it doesn't report an expected heat transfer rate, because of how many factors that value depends on.

My question: Is there a set of correlations or rules of thumb (given TDP, desired CPU temp, fan CPM, radiator size, and pump power) that I can use to make sure my old AIO is sufficient for my newer, more power-hungry CPU?

Specs:

TDP: 95 W (i7-9700K)
AIO Product: CoolerMaster MasterLiquid Pro 120
Radiator Size: 120 mm
Fan airflow: 66.7 cu. ft. per min. (max)
Pump Power: ??
Desired temp: 30 C
Ambient Temp: 23 C

Tristerin · April 16, 2020

My opinion is that a processor like that would require 240mm rad space to operate efficiently. Maybe a mild overclock with a single 240mm radiator at those ambient temps.

I have a 120mm AIO rad on my other R7 1700, it can handle all core OC to boost at stock voltages but once I start increasing voltages it doesn't contain the heat. When I had a 240mm AIO on my Ryzen Rig 2 in sig it could handle mild overclock no problem but I wanted to push it further so I went custom loop.

Can you? Yeah, keep an aggressive fan curve and use good paste (TG Kryo) but not expect any overclocking at all. Id also put it in push pull config.

(EDIT - just noted your desired temp - maybe at idle)

Foef_Yet_Flalf · April 16, 2020

3 hours ago, Tristerin said:

My opinion is that a processor like that would require 240mm rad space to operate efficiently. Maybe a mild overclock with a single 240mm radiator at those ambient temps.

I'd like to use a 120 mm rad because I'd like this build to fit in a mini ITX-specific case. If there is such a case that supports rads that big, I'd love to see it.

An alternative would to build a custom loop that puts two 120mm rads in series (and have a case that has two fan mounting points, but I'd rather not have to deal with a custom loop atm).