How hot is the radiator exhaust air?

M76

M76

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Has anyone ever measured this?

I'm curious. Because I'm planning a small footprint build, where I might have to put the AIO radiator under the PSU. So essentially the PSU would have to be cooled by the exhaust air of the radiator.

The air doesn't have much time to heat up inside the radiator, so I'm assuming the intake vs, exhaust temps can't be that different? My guess is maybe 5C° idle, which goes up to around 15C° under load? But this is purely hypothetical. I'm hoping someone actually has done some measurements so I don't have to.
 
Some closed loop coolers have water temp sensors - my Corsair H115i did. The water doesn't get really all that hot and the air passing thru the rad does not go up more than a couple degrees from intake side to exhaust side. The PSU would not suffer drawing in radiator air.
 
To the general question. I would vote a very decisive "it depends" haha.

How hot is your cpu going to be? If you plan on Ocing and running full bore a lot... Maybe an issue.

My last sff build had an aio on an Ocd 2500k with the 120mm rad input being the main airflow in. Got hot during a workout, but never reached a throttle point.

My current custom loop directs my gpu and cpu heat into the case. Does it warm up? Noticably. But still no throttling and I'd prefer it to negative pressure.
 
Guess I just have to try. Too bad I have to mod the case to make it work.
 
SticKx911 said:
To the general question. I would vote a very decisive "it depends" haha.

How hot is your cpu going to be? If you plan on Ocing and running full bore a lot... Maybe an issue.

My last sff build had an aio on an Ocd 2500k with the 120mm rad input being the main airflow in. Got hot during a workout, but never reached a throttle point.

My current custom loop directs my gpu and cpu heat into the case. Does it warm up? Noticably. But still no throttling and I'd prefer it to negative pressure.
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Yeah, its very much "it depends". It depends on the hardware. How much heat is it producing? It depends on the fan speed. Higher fan speed, lower air temps, lower dan speeds, higher air temps. It also depends on how many radiators you have. More radiator capacity, means that each individual spot will have lower temps. Lower radiator capacity means that all the heat comes out in one place, so higher temps. It will also depend on load and ambient temps.

So each build and configuration is going to be so very different that I'm not sure measurements are actually going to be helpful. I could measure the exhaust temps on my system, but I have a 45mm thick 3x140mm radiator up top and an 85mm thick 2x140mm radiator up front, which cool both my old 3930k CPU at 1.445v and 4.8Ghz and my overclocked Pascal Titan X.

My large radiator capacity will mean exhaust temps will be lower, but my old 32nm hexacore CPU at very high voltages and clocks will result in higher temps.. It won't be very relevant to an SFF build with the latest components and a small AIO.
 
M76 said:
Guess I just have to try. Too bad I have to mod the case to make it work.
Click to expand...

That's usually the way it is.

Can you try it out of the case? Install the AIO radiator over the PSU intake and see what the temps look like without missing the case?

It won't be a perfect model, but it may be better than nothing.

What does the PSU spec say about max operating temperature though?
 
Zarathustra[H] said:
That's usually the way it is.

Can you try it out of the case? Install the AIO radiator over the PSU intake and see what the temps look like without missing the case?

It won't be a perfect model, but it may be better than nothing.

What does the PSU spec say about max operating temperature though?
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It says up to 50C ambient.
 
M76 said:
It says up to 50C ambient.
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Hmm.

My guesstimate is that you will be fine. I can't imagine 50C exhaust air out of any system.

Exhaust air will be cooler than water loop temp. The water loop temp will be much cooler than the CPU temp.

At 50C you are at about as high as you'd want your loop temp to be without damaging your pump, and your CPU would likely be absolutely cooking.

I don't think it is likely in any scenario you'd get exhaust air temps that high. Probably won't ever get more than at the absolutely most Ambient + ~10-15C.

Will the system ever be run at 35C/95F ambient?
 
Zarathustra[H] said:
Will the system ever be run at 35C/95F ambient?
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Unlikely.

I've read that higher temperature usually means less life for a psu, and I've been using the same psu for over 4 years, so I don't really know how much life it has left. But it never ran at full capacity.
 
M76 said:
Unlikely.

I've read that higher temperature usually means less life for a psu, and I've been using the same psu for over 4 years, so I don't really know how much life it has left. But it never ran at full capacity.
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Higher temps do accelerate the decline of electronic components. I don't personally think its extremely relevant though. These things tend to outlast their usefulness anyway.

While I did say above that any comparison to other systems is probably not very useful, I figured I'd measure anyway just for the fun of it.

Currently my build is sitting at the desktop running a virus scan that is pinning one out of six cores at 100%.

Ambient temp is 20.3C, and air exhaust temp out of my top radiator is 26.9C, so 6.6C above ambient.

Once the scan is done, I'll reboot into windows and do a worst case with prime95 running on all cores and heaven benchmark running on the GPU, with fans set to max, to see what the temp is then. I'm kind of curious.
 
Sounds like a recipe for a very loud PSU fan. Make sure you have a larger capacity PSU than you need and one of the quieter brands, like Corsair. The EVGA ones are noisy, just avoid those.
 
Alright, so my testing is done. To summarize it all in one place:

Complete Idle on Desktop:
Fan Speed: 480 rpm
Ambient: 20.2°C
Exhaust: 25.9°C
Delta: 5.7°C above ambient

Single Core Destop Load:
Fan Speed: 480 rpm
Ambient: 20.3°C
Exhaust: 26.9°C
Delta: 6.6°C above ambient

Full Prime 95 Load 12 threads + Heaven Benchmark on GPU
Fan Speed: 1,875 rpm
Ambient: 20.2°C
Exhaust: 29.3°C
Delta: 9.1°C above ambient

Now as mentioned before, this may not be particularly related to a single radiator smaller loop setup like you are doing. Your temps will likely be a bit higher, but at least this is some sort of frame of reference.

My numbers are likely pretty different because I have a very oversized radiator capacity, and fast, high static pressure fans blowing through them at full speed. The relatively low temperature rise at full load is likely due to a combination of the heat being spread over a large amount of radiator capacity, and the fans putting a serious amount of air through the radiators, so it never increases in temperature that much.

As an aside, you can see that the GPU temp never went above 36°C even with the loop fully loaded by a combination of full GPU load and full all core CPU load.

44997221724_743c02890a_b.jpg


Edit: The forum software is making it very difficult to link to an external large resolution image without importing it and hosting it itself, which is a bit of a bummer. Try this direct link for the full size.

Presumably this is to fight the scourge of dead image links as threads get older, but - if toy like me - are in the habit of displaying a small external preview image, and putting url tags around it to link to the full version outside, this breaks that, which is a shame.
 
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Zarathustra[H] said:
Presumably this is to fight the scourge of dead image links as threads get older, but - if toy like me - are in the habit of displaying a small external preview image, and putting url tags around it to link to the full version outside, this breaks that, which is a shame.
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I've noticed that recently too. The way around is to let the forum host the small images, then put the url tags on the hosted thumbnails. It works that way.
 
M76 said:
I've noticed that recently too. The way around is to let the forum host the small images, then put the url tags on the hosted thumbnails. It works that way.
Click to expand...

I tried that, but the forum software was prioritizing the click to zoom function over the click to follow the external link, which is kind of a bummer.
 
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