Air flow direction for a top mounted AIO cooling system

[Ed.]

Need some opinions, the time had come to finally buy a computer as my old one was 11 years old. So I went to the local IT shop and ordered one to my specs, now that I have had some time to play around with it, I am questioning the direction of the air flow through the top mounted AIO radiator. The shop has set it up so the 3 x 120mm AIO fans suck the air in from the outside through the radiator into the case, so to my way of thinking it should suck the warm air out from inside the case and out to the room, and the air would be replaced by the cooler air coming in from the sides, front and bottom. Granted that the warm air inside the case would not cool the radiator as efficiently as having the cooler air blowing through it into the case. Having said that, air coming into the case after it gets heated by the radiator would just warm everything in the case.

The system that I bought is the Thermaltake Core W100 case, a MSI X670E Ace, Ryzen 79503XD, 64GB 6Ghz ram (2 x 32 GB sticks) 1Kw PSU, Deepcool 360 AIO, and a 1TB PCI-E Gen4 Nvme drive which will eventually be my main boot drive. I put my old GTX1070 card in it, a 5 x 6TB drive RAID running off a 9362-8I adaptor in RAID 5 mode, a LTO-5 tape drive, and an old 500GB SSD. This case is humungous and I have just ordered another 5 x 140mm fans for it, 4 to push air in through the filters and one for the top left back corner to help suck air out.

So over heating shouldn't be a problem however it just gives me a nagging feeling that the right way would be for the AIO fans to push the air out though the radiator into the room instead of the way it is set up currently. I am still playing with it and have the left side panel off and the CPU cores are sitting at 49-51C idling and the ambient room temp is 30C, have overclocked the cpu to 5.1Ghz so still more room to get higher speeds.

Am I overthinking it or does it even matter which direction the air goes through the radiator? Thanks.

 

[CyklonDX]

It matters if you plan on generating a lot of heat.
If you pull from top you will end up sucking your exhaust from back (as warmer air will make its way upward, and colder air downwards), and warming up all other components depending on radiator's temperature (if rad gets warm, you will additionally warm air passing through by few degrees.)

For proper air dynamics you should be sucking air from bottom, and front side; and throwing the hot air out from top and back. (just make sure the top exhaust is directed away from front intake fans.)

// workstation / pc's typically sit in corners of the room making the air bounce of the wall making its way upwards.
(not mine just stock photo)

 

[mattventura]

Ideally you want airflow to be front-to-back, bottom-to-top. There are a couple exceptions:
1. You still want to maintain positive pressure so it doesn't get too dusty inside.
2. If the machine is sitting on carpet, you do not want the bottom to be an intake.

 

[hkdio]

"Ideally you want airflow to be front-to-back, bottom-to-top" --> mattventura is right.

This is "ASHRAE standard" for data center cooling industry.
I had worked on Data Center for 10 yrs , all equipment must comply this rule of thumb
otherwise most DC can reject that equipment move-in coz it contaminate "cold aisle "



And for fan installation, it is depending on the CPU / GPU cooler design.

1. if Cooler is High fin density / thin metal heat sinks.
Fan installation objective is to "Push" as pertty much cool air to heatsink.


if Cooler is low fin density
2. Traditional design is Cooling Fan "Pull" hotair from heatsink to outside.


3. Some rack mount server also use low fin density cooler(eg: Tesla GPU), but airflow is "Push" air to heatsink
For that type of server / workstation, chassis require proper of cooling path design to avoid hot spot,
and need to add air blanket / space fillers in empty space.

For this reasons, put Graphics Cards with 3 fans into 2U server
is a very bad idea because it interrupt the air flow inside server.

 

[nabsltd]

1. You still want to maintain positive pressure so it doesn't get too dusty inside.

Most server chassis have a wall of fans in the front and basically nothing in the back, so that after a while, you find out your server room isn't nearly as clean as it looks, as all the dust ends up inside the chassis.

 

[hkdio]

Most server chassis have a wall of fans in the front and basically nothing in the back, so that after a while, you find out your server room isn't nearly as clean as it looks, as all the dust ends up inside the chassis.

That's why server use low fin density cooler to avoid dust trap inside server

Chassis dust is not a major issue as it can easily removed.

 

[Ed.]

Thanks for all the replies, this new box is way cooler than my last one, so heat isn't much of an issue, I was just curious as to why they set up the top radiator fans in the way they did, I just added another 4 x 140m fans to this case so a total of 7 pulling air in and 1 out, so the case should have a heap of air going through it.

I put 2 fans in front of the 5 disk Raid array, the case HDD support frame is a bit strange in the way it was designed in that 2 drives in each section virtually touch each over and they were getting warmer than I liked, (55C) not enough air going between them to cool them down from each other, so now they are down to 42C, added 1 fan at the top next to the AIO radiator so that seals the top off and the last fan at the top back helping to push the air out.

This case has a full length approx., 100mm wide meshed screen on the bottom as well as 2 more full length meshed strips on the right side of the case so the excess air has plenty of areas to push out from.

I am not planning on overclocking to the max as it is fast enough for what I do, although having said that I might just do it to just for fun and to see how much heat it will make.. The only real issue was my RAID card, I must have bumped the heat sink during the install and the chip got to 74C, the thermal pad wasn't making contact, so some new thermal paste and a small fan on the heat sink and the chip is 40C, so all in all, heat isn't a problem but as I said before I was just curious as to why they put the top fans the way they did.

I will play around with fan speeds to reach a happy compromise between cooling and noise level 'cause at the moment it is bit loud!