Custom Loop on a 120mm

[lukelex]

Has anyone ever tried to run a CPU+GPU custom loop under a 120mm radiator?

I'm planning a super small mITX rig, and am considering what temps you'd get out of it, but haven't been able to find any articles or videos of people doing it.

 

[Mackan]

Plenty of people have done that in a Sugo SG05/SG13 case. There are build logs and videos if do the right search. As for the temperatures, that depends totally on your components and the fan speed noise you can tolerate.

I've seen people cool a standard CPU (65-95W) + midrange GPU (100-150W) on a 120mm radiator with temperatures around 60-75C for the CPU and GPU, with a reasonable fan speed. So it's possible, but perhaps not recommended. High water temperature (close to 50C) could cause the pump to fail as well. Small pumps tend to be noisy, as well.

 

[tinyitx]

What CPU? GPU? Rad?

In general, the temp would not be very pretty. Let's say you prefer a delta T of 10C and assume you run the fan at about 1500rpm. a thin or thick 120mm rad can dissipate about 150-175W (rough estimate with Skinnee's graphs). So, you need to specify the CPU and GPU at least for more meaningful investigation.

 

[lukelex]

I'm looking at a 8700k stock + 1080 stock. I have both today under two 120mm single AIOs and they sit at high 40's low 50's under gaming load. If I could get them both at high 60's with a single 120mm I'd be happy.

 

[aquelito]

As mentioned by @tinyitx, very useful information right here :

https://web.archive.org/web/20141219123638/http://skinneelabs.com/triple-radiator-comparison-v2/4/

 

[Smanci]

Shouldn't high 60's be easily achievable with undervolting and small heatsinks? Quieter and more compact.

 

[tinyitx]

At the moment, you are using one AIO for the CPU and another for the GPU.
I think it is hard to accurately predict the temp if you use only one radiator to cool both.
Nevertheless, I will try a back-of-the-envelope style approach to estimate.

The 8700K has a 95W TDP and the 1080 is rated at 180W. If you use a single radiator to cool both for the total of 275W, let's say the cooling capacity of that single radiator is going to be shared between the CPU and GPU roughly in the same ratio (1:2) as their TDP. That is, 1/3 of the cooling capacity goes to the CPU and 2/3 goes to the GPU. Of course, this is in an equivalent sense only.

With the above estimate, you can try to simulate this effect by 2 methods:-

Method A)
Assuming your two current AIOs use only a single fan, thus the other side of the radiator is free.
You can then use a piece of paper or masking tape to cover up 1/3 (for the GPU) and 2/3 (for the CPU) of the other side of the radiator, reducing the airflow to simulate the effect that the cooling capacity is being shared.
Temp will rise and you can see if they will be above 60's C or not.

Method B)
If the two current AIOs are using dual fans in push-pull, then the above method is not do-able as it is impractical to do the covering up.
However, you can still simulate by reducing the fan speed of each AIO appropriately.

The relationship between fan speed and heat dissipation is not exactly a 45-degree straight line. That is, an 1/3 reduction in fan speed (in rpm) does not translate to an 1/3 reduction in heat dissipation (in Watts).
From a Skinnee's graph (for an XSpc 120 rad), I estimate an 1/3 power reduction corresponds roughly to an 1/2 reduction in fan speed.
Now, say, the current fan speed of your two AIOs while gaming is 3000rpm. Then I suggest reducing it to 1500rpm (for 2/3 power) and 700rpm (for 1/3 power).

So, while gaming, adjust the 8700K's AIO fan at 700rpm and the 1080's AIO fan at 1500rpm (by whatever software you are using to control the fan speed curve) and check the temp.

I reckon, this could be a first approximation of what will happen if you use a single 120mm radiator to cool both.

 

[Duality92]

I've seen a setup of SLI 980 Ti's and a 4790K watercooled by a single 280mm radiator, all three components oc'd slightly reached temps mid 70's IIRC, on OCN.

 

[Gautam]

It really should be fine IMHO. You're almost never going to be able to concoct a scenario where both your CPU and GPU are anywhere near 100% concurrently, unless you're doing something like mining on the GPU while folding@home on the CPU. It's still most likely going to be better than the stock cooler of a mini-ITX GPU with an L9i on the CPU. Which is pretty common.

 

[Duality92]

Asetek did release this too (Asetek 760GC CPU/GPU Cooler)


The R9 295X2 was also cooled by a single 120mm AIO with a small fan in the middle. of the card.