Concept Is it feasible to use the PSU as the only air exhaust in a closed case?

Veryaton

Average Stuffer
Original poster
Feb 28, 2017
65
31
I don't know if this is crazy or not, or something possible.

I want to make a powerful SFF with an cpu i9 8 gen (9700-9900K), using a Sugo SG13 box. The problem with this case is that it has no rear exhaust, and I've seen in another forum that a guy used the PSU as a rear exhaust, as you can see in the photo.

My idea is to use a PSU SFX-L, with the 120 cm fan down, and use it as exhaust of a Noctua NH-L12S cooler with double 15 cm fans. The case has an intake 140 fan in front.

Do you what think about this, is a solution that can works for these cpus, or is a madness that better not even take it into consideration?

Thank you
 

Necere

Shrink Ray Wielder
NCASE
Feb 22, 2015
1,707
3,223
Yes, and in fact, the ATX standard originally called for the power supply to act as the sole exhaust for the entire system. Of course, this was back when total system TDP was in the tens of watts, rather than the hundreds it is now for a higher end system.

The SG05 was actually designed for exactly this configuration, with the PSU drawing air up through Silverstone's own NT06-Pro cooler, the latter having an upward-blowing bottom-mounted fan. In principle there's no reason you can't do the same in the SG13, though it's questionable whether it's wise to do so with a higher TDP CPU, as you will be putting quite a bit of heat directly into the PSU.
 

Valantar

Shrink Ray Wielder
Jan 20, 2018
2,080
2,059
As Necere said, you'll be putting quite a lot of heat directly into your PSU. Most PSUs are rated for continuous operation at 40C ambient/intake air temperature, with good ones rated at 50C. The air coming off your cooler when pushing a 9700K or 9900K hard will be at least that hot - and while your PSU might survive higher temps, you're going to lose efficiency quickly (which will produce more heat in the PSU), and most likely degrade the quality of the power it outputs in any and all metrics (noise, ripple, etc.). Also, any capacitors will have their lifespans reduced significantly.

I take it you're planning on having a GPU in there as well. If so, which model? I'd try to stay on the conservative side here, no matter what.

Is this possible? Sure. Seems likely, as long as you're not running multi-day renders on this thing. Is it smart? That's debatable. At the very least you'll have to get a very high quality PSU and run your CPU as cool and slow as possible - remember that both the 9700K and 9900K consume far above 95W if MCE/MCT is enabled and/or your motherboard has loose PL2 settings (which most Z-series boards do, as they're "meant for overclocking"). All-core boost consumes ~180W on most 9900Ks. Of course your CPU cooler will be ensuring plentiful airflow through the PSU, but you'll still be running hot air into a small box full of heat-producing components. And the PSU fan will most likely go quite crazy.
 

Veryaton

Average Stuffer
Original poster
Feb 28, 2017
65
31
Thanks Necere and Valantar.

Ok, I didn't know this, that the PSU was thinking for air exhaust.
When I said the config is a closed box is because I want the SG13 into a flying case. But now I am thinking that the flying case is not necessary that cover full SG13, I can to let without cover the last third, where are the air vent holes, and let air exhaust with easier.

In this case (air vent holes open), what do you guys think is better? an ATX PSU that cover a low profile cooler, or a SFX PSU in a normal position (fan up) with a better cooler as Noctua NH-L12S?

The NH-L12S is compatible with the 9700K, but I don't know if with the air holes open is enough or it could have problem for heat without a fan exhaust...

Yes, the GPU would be a Quadro RXT 4000, is a single slot blower card with 160W.
 
Last edited:

Veryaton

Average Stuffer
Original poster
Feb 28, 2017
65
31
Is this possible? Sure. Seems likely, as long as you're not running multi-day renders on this thing. Is it smart? That's debatable. At the very least you'll have to get a very high quality PSU and run your CPU as cool and slow as possible - remember that both the 9700K and 9900K consume far above 95W if MCE/MCT is enabled and/or your motherboard has loose PL2 settings (which most Z-series boards do, as they're "meant for overclocking"). All-core boost consumes ~180W on most 9900Ks. Of course your CPU cooler will be ensuring plentiful airflow through the PSU, but you'll still be running hot air into a small box full of heat-producing components. And the PSU fan will most likely go quite crazy.

Yes, my idea is using it for render, but not a full day :-) . Then better I discard the idea of an ATX PSU as air exhaust.

But with an i7 9700K with a limit of 160W in bios, the NH-L12S can works, don't?
Perhaps better the front 140mm fan as exhaust air than intake air?
 
Last edited:

MarcParis

Spatial Philosopher
Apr 1, 2016
3,496
2,536
Definitely this idea of psu used as lone exhaust fan is a mixed bag.

Back to Sugo SG04 (old days of first SFF case..;)) I did this setup with reliable PSU (Corsair 1000W or Seasonic 850 Silver) and an core i7 920.

It should work however I saw some restrictions/drawbacks :
  • Don't consider semi fanless psu...your psu fan should spin all time
  • Don't consider to use in intense way your cpu (gaming is ok but forget overlclocking or heavy & long cpu load)
  • Expect PSU failure/lifespan reduction either on its capacitors and its fan motor
Other option is to use 120mm aio with radiator put on front panel, with fan setup in exhaust mode.
 
  • Like
Reactions: Valantar

Veryaton

Average Stuffer
Original poster
Feb 28, 2017
65
31
Other option is to use 120mm aio with radiator put on front panel, with fan setup in exhaust mode.
Thanks
Yes, but this setup is for a moving equipment, always in travel (for that is the flying case), I don't have a good experience con liquid AIO in this situation, I prefer an air cooler.
I am watching entries with SG13 in Pcpartpicker, there are several configs with the NH-L12S, and it seems a good options...
 

MarcParis

Spatial Philosopher
Apr 1, 2016
3,496
2,536
Thanks
Yes, but this setup is for a moving equipment, always in travel (for that is the flying case), I don't have a good experience con liquid AIO in this situation, I prefer an air cooler.
I am watching entries with SG13 in Pcpartpicker, there are several configs with the NH-L12S, and it seems a good options...
Sure Aircooling is way more suited (and lighter) than watercooling if you plan to move a lot with it.
To help cooling, you can still underclock and undervolt any cpu to match a lower tdp (65w or even 45w)...this should be a safer path..:)
 

Valantar

Shrink Ray Wielder
Jan 20, 2018
2,080
2,059
Yes, my idea is using it for render, but not a full day :-) . Then better I discard the idea of an ATX PSU as air exhaust.

But with an i7 9700K with a limit of 160W in bios, the NH-L12S can works, don't?
Perhaps better the front 140mm fan as exhaust air than intake air?
Exhausting air through the front might be better, though that depends on how well ventilated the case is to ensure that enough air actually gets in (otherwise the fan will just be creating turbulence, not moving air, and you'll be left with a hot box for your components).

As for the NH-L12S being sufficient for a 160W CPU, it might be, the bigger question is whether venting 160W of heat into your PSU for hours on end is a terrible idea, or just a mid-range bad one. I'm leaning towards the former. If you're travelling and doing multi-hour renders, it sounds like this is a PC that you actually need working. The risk of cooking your PSU (and it dying at some random point, likely while it's under load, i.e. doing a render) thus sounds like one you wouldn't like to take - getting a hold of a sufficiently powerful replacement SFX-L PSU in an unfamiliar place on short notice? Not going to be easy.


What applications will you be working in? Depending on the workload, a Ryzen 7 2700X might be a better fit for your thermal limitations, and the Zen architecture does very well for most rendering workloads. At least according to Anandtech, it's slightly faster than a 9700K for their rendering benchmarks (some faster, some slower, so as I said, it depends on your workload) while consuming slightly less power. Or you could go for the 65W Ryzen 7 2700, get rid of your cooling problem entirely, but get slightly slower render times.
 

Veryaton

Average Stuffer
Original poster
Feb 28, 2017
65
31
The use the PSU as exhaust is already discart, it was only a idea, seeing that someone had used it but since the beginning it appeared odd.

Ryzen is not a option because I need a motherboard with thunderbolt. This port is very versatil for storage, expansion dock, etc. Mainly is for run Davinci Resolve, and is important a good CPU-GPU combination, and all this in a small body, if it is possible...

Sugo GS13 is the better case I have found, with air front intake.
 

Valantar

Shrink Ray Wielder
Jan 20, 2018
2,080
2,059
The use the PSU as exhaust is already discart, it was only a idea, seeing that someone had used it but since the beginning it appeared odd.

Ryzen is not a option because I need a motherboard with thunderbolt. This port is very versatil for storage, expansion dock, etc. Mainly is for run Davinci Resolve, and is important a good CPU-GPU combination, and all this in a small body, if it is possible...

Sugo GS13 is the better case I have found, with air front intake.
I see. Thunderbolt is handy (I use it to dock my work laptop, it's by far the best docking solution I've come across), but I've never seen a need for it in a desktop. I suppose a portable renderbox might need to connect to DAS RAID units and other storage solutions where USB 3.1G2 is insufficient though, so I understand that :) I'm looking forward to Intel's removal of TB3 royalties starting to trickle down to more desktop boards and AMD-based laptops including it.

Have you considered a case with a less boxy layout, like the Fractal Design Node 202, Silverstone RVZ01 or FTZ01? Flat layouts like those limit CPU cooler height, but provide fresh air to all components, and should fit in a standard carry-on bag for travel. There are plenty of other options in the "flat layout SFF case" category too.
 

Veryaton

Average Stuffer
Original poster
Feb 28, 2017
65
31
Well, my needs are very especifics, the case always will be into the flying case, simply take off the front and rear cover and the equipment is ready for work. I don't know if this is well explain.
For that I am looking for a case with front to rear airflow, with laterals closed.