DIY Perks - Invisible Desk PC

AlexTSG

Master of Cramming
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Jun 17, 2018
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I'm putting this in Off Topic, as this PC is certainly not small form factor by volume.

However, in a lot of respects the fact that the desk is only 5cm thick makes it necessary to build as though it were.



I was wondering if the cooling would have not been better and quieter if some larger fans had been mounted on the inside of the bottom plate of the desk, drawing air up from underneath, perhaps with a shroud to direct airflow.

What do you think of it?
 
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Phuncz

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I'm amazed that forty (?) 40mm fans aren't making a more buzzing sound. Also powering and wiring those forty fans decently is going to be a challenge.
So your suggestion to use larger fans horizontally makes more sense. though too large of fans will have a much bigger dead zone in front of the fan hub and will have issues with air bouncing back. I'd consider a watercooling setup with fans pulling in from the bottom and the radiator exhaust at a hole in the top to get a performance optimized flow-through path.
 
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AlexTSG

Master of Cramming
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Jun 17, 2018
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I'm amazed that forty (?) 40mm fans aren't making a more buzzing sound. Also powering and wiring those forty fans decently is going to be a challenge.
So your suggestion to use larger fans horizontally makes more sense. though too large of fans will have a much bigger dead zone in front of the fan hub and will have issues with air bouncing back. I'd consider a watercooling setup with fans pulling in from the bottom and the radiator exhaust at a hole in the top to get a performance optimized flow-through path.

He does mention in the video that Linus Tech Tips is working on a similar project, but they plan to use watercooling. I'll be interested to see that when it comes out.

Perhaps 80mm fans at either side mounted at a 45 degree angle blowing air towards the center with a suitable shroud would be a happy medium.
 

Phuncz

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@AlexTSG that video has gone up already short after the one from DIY Perks:


Or atleast I think this is the one, how many desk builds does LTT do at the same time ? :D
 
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russdyer

Cable Smoosher
Oct 6, 2020
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10
He does mention in the video that Linus Tech Tips is working on a similar project, but they plan to use watercooling. I'll be interested to see that when it comes out.

Perhaps 80mm fans at either side mounted at a 45 degree angle blowing air towards the center with a suitable shroud would be a happy medium.
I'm very interested in making a build like this with probably a total height of 2.5" - do you know of shallow shrouds to redirect air towards the center in that small of space? or would building a 45 degree angle from plywood above the fans work to direct towards the opposite side of the desk?

wonder how well something like this would work out? - https://www.thingiverse.com/thing:4050067
 
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jmarin

Airflow Optimizer
Mar 8, 2018
258
177
wonder how well something like this would work out? - https://www.thingiverse.com/thing:4050067
I think that would work reasonably well as long as it was able to draw in air unobstructed. Would provide more volume at lower RPM and be quieter, although in the DIY Perks video, it seems the noise was pretty minimal. A handful of 140mm fans would be much cheaper and easier to power than the bushel of 40mm fans though
 

russdyer

Cable Smoosher
Oct 6, 2020
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looking at something like this and wondering your thoughts on airflow (x3 120mm on each side of desk, one set intake, other set exhaust) with CPU/GPU fans exposed the exhaust their heat. wondering if most heat inside desk will be exhausted by CPU/GPU fans making the x3 set of exhaust fans redundant (or should CPU/GPU fans be enclosed like a normal case and rely on exhaust fans on opposite side instead). maybe better to move exhaust fans towards the middle instead?

 
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Phuncz

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I'd consider putting the exhaust fans in the middle and change the exhaust fans on the left to intake, so you can have a second system on the left side of the enclosure. Additionally I'd make ventilation holes (with mesh to prevent bugs from entering) at the back or bottom rear to offload the overpressure created by more intake fans if you go with a second system.
 
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russdyer

Cable Smoosher
Oct 6, 2020
8
10
great, thanks for the help. Do you think it's necessary to have deflectors to direct air towards the components or is just having intake coming from bottom enough without directing it?
 

jmarin

Airflow Optimizer
Mar 8, 2018
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I think before you decide on how you are mounting the fans/deflecting air, maybe do a small scale test with a fan to see what would be most efficient. Maybe mounting them on an angle would make the deflector more efficient versus having them horizontal and making the deflector do all the work
 

Phuncz

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great, thanks for the help. Do you think it's necessary to have deflectors to direct air towards the components or is just having intake coming from bottom enough without directing it?
I would expect they would improve airflow if you have positive pressure (more intake than exhaust airflow) but I think it will be minimal improvements with negative pressure (more exhaust than intake airflow).
 

russdyer

Cable Smoosher
Oct 6, 2020
8
10
I'm putting this in Off Topic, as this PC is certainly not small form factor by volume.

However, in a lot of respects the fact that the desk is only 5cm thick makes it necessary to build as though it were.



I was wondering if the cooling would have not been better and quieter if some larger fans had been mounted on the inside of the bottom plate of the desk, drawing air up from underneath, perhaps with a shroud to direct airflow.

What do you think of it?

So, after a few months I have my finished product - instead of the tiny fans, I settled on fabricating ramps to help guide the four 140mm intake fans. I'm super proud of the build and temps are pretty great, but need to do some more benchmarking.

Finished product:



Build log - https://smallformfactor.net/forum/threads/air-cooling-advice-on-desk-pc-build.15049/
 
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