Question Custom PC case (desk) cooling

Dec 13, 2020
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Need some expert opinions on this one!
I have a client who originally wanted me to build him one of those 'invisible' type PC desks, where you can't tell there's a computer in it and don't see many wires; basically, it looks like a normal table. He gave me the list of the larger components he had and I told him that would not be possible:
  • Asus RTX 3070 TUF (360mm radiator with 3X fans)
  • EVGA AIO CPU cooler (360mm radiator with 3x fans)
  • Gigabyte 850W PSU
  • Asus X570 Motherboard
So he gets that (luckily), and still wants it built into a table, but make it as invisible as possible and still maintain the table size of 30 x 66". The concept I came up with is to build it all in a small, compact box that goes under the back middle of the table. This way, you'd have to get low to be able to see it under there, and with the height I'm aiming for, tuck his legs in without hitting the thing.
I'm still concerned through with cooling. Here is the concept I have come up with:
View: https://imgur.com/a/OF8Kf2a

Each box on the graph is 1"x1", and the box height would be 6" max. 'Top' of the image would be the rear of the desk.
The GPU and CPU fans would pull cool air from outside across the radiators. So that's six 120MM fans on the intake. But for exhaust, the only thing I have room left for are two 92mm fans above the ports on the MB, and a 120MM on the right side. Will that be enough to remove the hot air? I can put another 120mm fan to the left and facing down of the one that's already in there, but I don't know how well exhaust works in that direction.
Comments would be greatly appreciated. I plan on building this box out of plywood first as a proof of concept and run some benchmarks on it before building the real thing, which will be integrated into the table itself and made of solid walnut.
 

tennis2

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Not sure why that hardware list isn't possible....


Have you seen this video?

I don't like his fan choices (mount larger fans to the base and deflect the air inside to move it sideways)

To your cooling question. Most mid to high tier gaming PCs have two or three 120mm intake fans and 1 exhaust.
 
Dec 13, 2020
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He actually showed me that video originally. I could make it where the GPU and the CPU cooler face the bottoms and pull cold air that way, and then the limiting thickness is the PSU at 4". But I'm worried that that I wouldn't be able to get things to exhaust well with it spread around. I'm thinking with that, the warm air off the radiator will need to be pushed out so it doesn't collect. For that, with limiting height, I'll have a hot wheels track of small fans moving things around.
 

tennis2

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Nah, that's what im saying. In the video, he uses tiny (noisy) 40mm fans so they can be blowing air horizontally though the desk. But that's not necessary at all. Mount a couple 120mm fans blowing up on one side, and a couple 120mm fans blowing back down on the opposite side. The air will flow from the intake to the exhaust side just fine because there's nowhere else for it to go.
 
Dec 13, 2020
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Would 120 mm fans at an angle (to fit in a 4" enclosure) work? No waywould they fit standing up.
The thing that has me worried is if the CPU and GPU face down (and say the bottom of the top is mesh to get air in), I have cold air blowing in, across the radiator, and then it collides with to top of the desk. Wouldn't I need a fan pushing this accumulated hot air away from this area? With the current set up, the air goes through the radiator into the case and is pull out by the fans inside. So got a system going for it.
 

tennis2

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If you want to angle the fans, that's fine, but unnecessary and it makes fabricating the mounts for them more difficult.

On the GPU, use foam tape to create a seal around a custom cutout (face plate with fan holes to match the GPU fans that you mount to the bottom of the desk that can be remade later if the GPU changes). GPU intakes fresh air from under the desk, then blows its hot exhaust air into the air channel inside the desk, but the air has already passed through the AIO and over the mobo, so the GPU is the last stop before exhaust.

[Add] The GPU doesn't mount to the mobo, use a riser cable or a 90 degree adapter.
https://www.amazon.com/stores/page/5EC0F659-D8DC-498B-BC34-CC57D304D2D6

Using an AIO makes CPU cooling easy obviously.
 
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Dec 13, 2020
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Nofanneeded, I actually based the layout on a case I forgot the name of, but it's a slim case. But the dude wants this in solid walnut all the way through so I can't do as you say and bolt a case underneath.

So Tennis, that was somewhat my original design before I got concerned with the exhaust. The limiting factor in the build is the depth of the power supply at 3.5". Originally, I was going to make a thinner, longer box with, as you point out, cutouts for the fans on the GPU and CPU cooler. I have 66" length wise, so I might as well work with it. It would go, from left to right, GPU (air from table bottom, using a riser to position like you posted), MB, CPU cooler (air from table bottom), then PSU (air from table bottom). The length and width would increase, but for the design, I would make the whole table "top" that thick. Like image a desk with drawers, but no drawers; it's just the thick. I've mad many a table (not with computers in them...) for others like that.
So I would bump up the inside depth to 3.7" to get 92mm fans in there. Shifting my MB an inch from the back wall, I could fit three across the back for exahust. I could bump that up to four or five by moving things left and right more because again, I got plenty of length to play with. But I was concerned that wouldn't be enough, considering how much air I'm moving in the case.
I guess I'm still confused on the concept. I have the fans taking in cold air, across the radiator, then it's in the case. I'm seeing it as, because how tight it is in there, it goes through the radiator, hits the inside top of the desk, and starts 'accumulating' around the radiator because nothing is 'pushing' it away outside of hitting the top and dispersing however much it does. The exhausts are pulling, but the volume inside the case is so large, it's not able to pull it enough, get it out fast enough, and temperatures will keep rising, albeit slowly.
Am I not envisioning this right? Am I overthinking this? Every diagram I look at for PC case air flow shows cool air coming in and 'pushing' hot air around the components towards the exhaust fans. I'd be missing that push aspect to build it in this other way, no?
 

nofanneeded

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Sep 29, 2019
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Nofanneeded, I actually based the layout on a case I forgot the name of, but it's a slim case. But the dude wants this in solid walnut all the way through so I can't do as you say and bolt a case underneath.
Fine then , make a solid walnut compartment and put the PC case inside it.

you dont have to go from scratch at all.

actually this would be easier no need to drill holes inside any case , just put the case inside the walnut compartment . and this way also you can use any tower or desktop. and slide it inside the compartment...

Just make a box of walnut and slide any case inside..

you can mount fans on the compartment as well and the case inside you just put it without doors and covers , just inside frame
 
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Dec 13, 2020
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Tennis,
See this picture:
View: https://imgur.com/gHw3Gn1

This is what we were discussing, air from the bottom. Would six 92mm fans, or seven 80mm preferably, along the back be sufficient to draw hot air out of the case? Or would I want to put fans to the left of the GPU and right of the CPU Cooler to push that hot air towards the middle of the case, then let the exhaust fans pull all that out? I guess under those fans I would put mesh so they would be getting cool air from outside to blow around.

Nofanneeded, I love working with wood so it's not about starting from scratch or whatever. What he's asking I can hammer out in a matter of hours, and that includes waiting for glue ups to dry. This guy is a Youtube star or something (I've built sets for him before) so cost isn't an issue.
 

nofanneeded

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Sep 29, 2019
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Nofanneeded, I love working with wood so it's not about starting from scratch or whatever. What he's asking I can hammer out in a matter of hours, and that includes waiting for glue ups to dry. This guy is a Youtube star or something (I've built sets for him before) so cost isn't an issue.
okay if you insist ... I will help you out here.. but for last try , check Thermaltake open frame cases .. they are wall mountable , you can mount them inside the wooden box.

https://www.thermaltake.com/products/chassis.html?cat=190

if not , I will help

1- First , the Motherboard has PCI express Gen 4.0 slots , be sure the PCIe cables are Gen4.0 and not 3.0

2- about the Radiator , you should drill FANS holes below it ..

3- you need to make it like a wooden drawer that slides from behind for maintenance ...

4- what motherboard model are you using? and how many slots ?? there is no point in using FULL ATX huge motherboard in there .

5- Use SFX-L power supply to save space as well . 750 watts one.
 

tennis2

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  • An SFX or SFX-L PSU is only 2.5" tall. I suppose this depends on whether you're trying to preserve enough height to include low-profile expansion cards in the system at a later date(?).
  • You're going to want to position the PSU between the mobo and GPU because of cable length on the PSU. Especially if you use an SFX or SFX/L PSU.
    • If you go SFX/SFX-L, pay attention to cable lengths to reach the EPS12V at the top of the mobo, especially if you insist on using an ATX board (see below)
  • Airflow per your drawing (flowing right to left):
    • 360mm radiator is your intake from underneath the table.
    • Air blows over top of mobo
      • mATX would be a better choice if you want to retain 4 RAM slots, otherwise mITX. The GPU ribbon cable is going to cover all the expansion slots below the top x16 slot, so an ATX board is a waste of space. If you're planning enough height to fit low profile expansion card(s) into the system at a later date, an mATX board with an x1 slot closest to the CPU is a good choice. Otherwise, again, mITX. Either way, get a board with onboard/integrated WiFi since that's the most common expansion card add to any system (USB WiFi adapters are fine, but ultimately not as good).
    • Air blows through/around GPU (GPU shroud is sealed against the bottom of the case so its fans intake fresh air from under the desk (hole cutouts) and the exhaust air obviously enters the airflow channel of the system.
    • 2-x120mm fans positioned to the left of the GPU, mounted parallel to the base of the table are your exhaust (exhausting air back down, underneath the table). If you want to undertake the fabrication challenge, you could angle the exhaust fans within the 2.5" of thickness so they're directing air to the left edge of the desk. Ultimately, the distance between intake and exhaust should be enough here that you can probably get away with horizontal exhaust fans.
      • No need for 80/92mm fans exhausting out the back. That adds unnecessary tabletop thickness because they'd need to be located above the mobo IO panel.
      • Although the PSU is between the mobo and the GPU, it doesn't need to be included in the airflow channel of the system since it intakes air from under the desk and exhausts it out the back of the PSU unit.
 
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USAFRet

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A desk drawer is little different than a regular PC case.

Lay a case down on its side.
Place the PC components in the same locations and orientation they would be in the case.
Carve up the drawer appropriately.
 

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