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Best positioning of the fans on the H150i


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I shall be building a rig consisting of;

Case-Corsair Obsidian 750D AirFlow Full Tower ATX

Motherboard-ASUS ROG STRIX AMD Ryzen X470-F GAMING AM4 ATX (when it comes back from RMA as it did not POST to BOOT)!:mad::(:

Processor-AMD AMD Ryzen 7 2700X Gen2 8 Core AM4

Memory-Corsair Vengeance RGB PRO Black 16GB 3200 MHz DDR4

PSU-Corsair HX850i 850W Full Modular

GPU-AMD Radeon RX 590 Red Devil 8GB GDDR5

Liquid cooler-Corsair Hydro H150i PRO RGB

Fan Single Pack Corsair ML140 PRO RGB LED 140MM PWM Premium Magnetic Levitation Fan plus Twin Fan Pack Corsair ML140 PRO RGB LED 140MM PWM Premium Magnetic Levitation Fan + Lighting Hub (To replace the Obsidian 750D AirFlow case fans.)

In addition, 1x Fan Corsair 120mm ML Series ML120, 7 Blade, Premium Magnetic Levitation Fan to fit at the bottom pushing air in after removing 1 HDD caddy.

The rest is an M.2 500GB 960 EVO PCI Express 3.0 x4 NVMe Solid State Drive

HDD-Seagate 1TB 3.5" SATA 3 Hard Disk Drive/HDD ST1000DM010

Optical Drive-ASUS x24 DVD/CD Re-Writer with M-DISC Support

Commander PRO-Corsair Commander PRO Digital Fan and RGB Lighting Controller

Lighting Strips-Corsair RGB Lighting PRO Expansion Kit Strips for Commander PRO/Lighting Node PRO


My question is one that I find confusing to say the least, and it is;

Which way to fit the fans on the H150i?

If the fans are to cool the radiator as @DevBiker states in A.3 of his article here then by that I understand that the fans should be placed above the radiator blowing cool air in as shown in my picture AIR IN 1. Not only does it meet the answer to A.3 but also ensures a positive pressure in the case.

So, am I correct in my assumption ( I stand to be corrected) or should I place the fans on the H150i in the following configuration;

AIR IN 2 or

AIR OUT 1 or

AIR OUT 2 :question:

Edited by scopio
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In a 750D there can be only once placement for a 360mm. That is up top with the drives bay gutted. Given the location and case, you are going to want to position the fans to blow out through the top as exhaust. It doesn't really matter if they are above or below the radiator, although my preference in that position is normally below so the fan blade only interacts with one surface instead of two, it lets you see if the fan is spinning, and most of the time we buy nice fans so we can look at them. However, the reverse is true and I have put them above to hide ugly or mismatched fans.


All this stuff about intake vs exhaust optimization and pressure balance is mostly theoretical or perhaps even philosophical. I am an optimizer. I will spend hours and hours thinking of ways to reduce my case temp by 1C. Is important? Absolutely not and it has no meaningful impact on any use, I just have strange hobbies. For you, the top 3 inches of your case is always going to be slightly warmer than the bottom three inches. As such, your resting coolant temperature with the radiator in the top position may be 1-2C warmer than if it were front mounted. So if you had a perfect cube case that could have radiators mounted on any side in any position (let's call that the Air 940 - please:), you could put things any place and compare them all. However, like nearly everyone else you are constrained by the physical case and component size. I cannot remember anyone on here running a 750D in a non-traditional set-up (front/bottom in, top/rear out). It works well for a reason. In a smaller case, GPU waste heat can have a noticeable effect on radiator temps. The 750D is not a small case. There still may be some effect for very long GPU loads, but then we all live with this one way or another and you can always flip the fans over and see for yourself. However, the most likely results is a disturbed airflow cycle in the middle of the case that ruins your air flow efficiency.


As for all this pressure stuff... aside from crazy fan counts (7 intake/1 exhaust etc.) you can always simply change the fan speed to adjust the intake/exhaust balance to your liking. However, the 2x140 front, 1x140/120 bottom vs 3x120 top and 1x140 rear is actually intake positive. Don't forget the radiator is massive restriction to airflow. Those 3x120 on it will only move about half their specified airflow when at maximum, a speed you will never need to use on the H150i. Those fans are going to sit up there comfortably at 1000-1200 rpm and slowly vent their heat out of the case. The rear exhaust fan will handle the GPU waste heat. Front/bottom intake creates a clear airflow path toward the top rear corner.

Edited by c-attack
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Thanks c-attack for a very clear explanation. I will put the AIO fans as exhaust below the radiator and the new ML120 fan as an intake on the bottom. Sorry for the urgency but I am in the process of making all the connections.
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