I have a pre-built computer from iBuyPower that came with AIO (All-In-One) liquid cooling system. Quality of iBuyPower's AIO system is very suspect. On reddit, there are many people reporting issues with AIO going out. Unfortunately, only 5 months of owning my computer, my AIO is also going out. So I went thru RMA to replace the AIO system. When I replaced the AIO, I decided to change the configuration (from exhaust to intake for radiator cooling). And I got significant reduction in CPU temperature.
I will go over AIO and Fan introduction first. Then my AIO setup after that. You can jump to the last section if you just want to see my results with intake vs exhaust for AIO radiator.
AIO Overview
AIO stands for All-In-One, which is a self contained liquid cooling system. There is a head with a heatsink (that goes over the CPU); radiator (where heat dissipation takes place); fan to cool the radiator; and tubing that connects the head to the radiator. AIO is pre-built and designed so that user does not need to (or cannot) maintain the system. Positive is that it is easy to install. Downside is that when coolant level becomes too low over time, there is no maintenance that user can do.
On the other hand, there are custom kits for cooling system. This means user has to build the tubing to run the coolant. This typically involves cutting the tubing, using l-shaped connectors, and filling the system with coolant. Obviously, one negative is the difficulty and amount of work involved to install this system. The positives are customization, can look great, and user can maintain the system.
AIO comes in various sizes. The size refers to the radiator size. Some common sizes are 120mm, 240mm, 280mm, 360mm, 420mm, etc. 120mm means radiator is roughly squarish and is the similar size as a 120mm fan. 240mm has rectangular radiator that is 2 x 120 mm fan. 280mm is 2 x 140mm fan. 360mm has even longer rectangular radiator that is 3 x 120mm fan. 420mm is 3 x 140mm fan.
AIO has a pump in AIO that moves the coolant from head/heatsink to radiator and back. The pump can be placed at different locations. One common design is to have the pump in the AIO head. Other designs have pump in the radiator.
The AIO that comes with my iBuyPower pre-built system is a 120mm AIO. It is very similar to the following AIO from Cooler Master, Corsair, and NZXT. In fact,
AIO vs Fan
AIO does the equivalent job as CPU heatsink and fan. There are general pros and cons of each design.
AIO advantage is that it is quieter. When the pump is running, there is no sound. However, that doesn't mean computer won't have sound. The radiator fans create sound. And there are other case fans and GPU fans that will make a lot of noise when system is at full load and fans are spinning at maximum rpm.
AIO disadvantage is usage lifetime. There is always some amount of coolant loss. The tubing and connectors will always allow some permeation. So over time (months to years), the coolant gets lower and lower. This by itself might not be a problem. But the liquid pump is designed to pump fluid, not air. When coolant level is low enough, air can get into the pump, causing the pump to fail prematurely.
CPU fan advantage is price. Cheap CPU heatsink and fan starts at $15, versus $50 for AIO. Expensive, quality CPU heatsink and fan gets up to $120, versus $250 for large 360mm AIO. Another advantage for fan is longevity. The CPU fan/heatsink will last as long as the fan. And if the CPU fan fails, most units have fans that are replaceable.
Here is an example of high-end Noctua tower heatsink with 2 fans:
In terms of performance, there is not significant difference between AIO vs fan. There is a bigger performance difference is due to price, size of heatsink, fan effectiveness, and AIO radiator size.
AIO Configuration: Intake vs Exhaust for Radiator Fans
For AIO radiator configurator, the key considerations are:
Where to place the radiator (front vs top vs bottom)
Direction of radiator fans (intake vs exhaust)
Radiator fan setup (push vs pull vs push+pull)
On the cooling, the maximum heat exchange occurs when there is largest temperature difference between fluid temperature in radiator and air temperature. So when radiator is being cooled by intake air (cool air from outside the computer case), this is most effective setup for cooling the CPU.
There is a downside with intake setup. The intake air that goes thru the radiator now becomes heated by the radiator and is being fed into the computer case. This can have negative effect on System and GPU temperatures.
On the other hand, when radiator is being cooled by exhaust, hot air inside the case (heated up by motherboard, GPU, CPU) is used to cool the radiator. The temperature delta is lower between the air and the radiator. This is not the most effective CPU cooling for the radiator.
My AIO Radiator Configuration:
On the left is how iBuyPower pre-built system was originally configured. Radiator was at rear of the computer, and radiator fans were in exhaust mode. Note there were 2 radiator fans in front and behind the raditor, in push+pull mode. I kept this push+pull mode in both exhast and intake setups. Push mode has fan blowing air into the radiator; pull mode has fan blowing away from the radiator; push+pull mode is a sandwich with 2 fans. There are some YouTube videos that compared push vs pull vs push+pull modes. The differences are typically small (< 1-2 deg C difference). iBuyPower did use push+pull mode, which should be the best method, especially with weak fans used in iBuyPower system.
A while back, I added a fan (green in the diagram) at top rear of the computer to aide in getting hot air out of the system. This was done before I changed the AIO/radiator fan configuration.
When I replaced the AIO, I wanted to move the radiator fan to intake mode. I cannot leave the radiator at the rear of the case, because that will not create air flow needed in the case. My options are to place the radiator at front or top. Bottom is not an option for this iBuyPower computer case.
The most natural position for intake is at the front. But I decided against that for several reasons.
iBuyPower case's front intake air flow is not optimal. The entire front panel is made of plastic/glass. There are inlets holes only at 1 edge of the front panel. Not sure why iBuyPower does not make holes all around the front edges for air intake.
I didn't want to use the RGB fan for the radiator, because those RGB fans are 1500 rpm and have low CFM. These RGB fans works fine as case fans, but not as radiator fans, which need to work with higher resistance.
Lastly, if I replace one of the front RGB fan with the radiator fan, the aesthetic is affected. I will have 2 RGB fans at the front and does not look balanced.
So I'm left with top of case as the best placement location for radiator. I put the radiator at top front, which leaves room for an exhaust fan at top rear. And based on the results below, it works well.
To compare the configurations, I just played several games (around 1 hour) of Valorant. I used HWiNFO to check maximum temperatures. I highly recommend HWiNFO. (Link https://www.hwinfo.com/). It is a free software. This can monitor temperature of CPU, GPU, motherboard, SSD, HDD; along with fan speeds. And it also monitors other parameters like clock frequency, voltages, disk read/write, etc.
Here are my results:
​ | Radiator Fans in Exhaust Mode | Radiator Fans in Intake Mode | Temperature Delta |
CPU Temperature | 71 deg C | 60 deg C | -11 deg C |
GPU Temperature | 68 deg C | 72 deg C | +4 deg C |
System Temperature | 43 deg C | 48 deg C | +5 deg C |
The direction of change is as expected. When I changed radiator fans from exhaust to intake, CPU temperature went down (by 11 deg C), but GPU and System temperature went up (by 4-5 deg C).
Is this better? I think so. Based on my own experience, plus what I learned online, I am now a firm believer that radiator fan should be in intake mode. It's like a car. The radiator is in the front where it is cooled by cold air from outside.
My Computer Spec
CPU: Intel i7-12700F
GPU: GeForce RTX 3060
Motherboard: Gigabyte Z690 UD AX DDR4
Memory: 16GB (2 x 8GB) DDR4 3200MHz
SSD: 1TB M.2 NVMe
SSD (I added): 2TB M.2 NVMe
HDD (I added): 4TB
PSU: 600W 80 Plus Gold
Link to Other Tests with Intake vs Exhaust
Here are couple YouTube videos that compared intake vs exhaust. Direction of the result is consistent with what I observed. However, the amount of temperature change did differ in each case. Not surprising, as they have different CPU, GPU, AIO, and case.
AIO Setup
Lastly, the setup of the AIO system can affect longevity. Pump, tubing, and radiator connection should not be highest points in the loop, to avoid getting air into the pump. See this video from JayzTwoCents, who sums up the issue quite well: https://youtu.be/DKwA7ygTJn0.
Jayz's video was actually in response (or follow-up) to Steve's much longer video at Gamer Nexus: https://youtu.be/BbGomv195sk.
Whatever configuration you try, at least follow the guideline. When AIO starts to fail, there can be rattling, clicking, buzzing noises. This is when air gets into the pump, and the pump is now trying to move air. Again, these fluid pumps are not designed to move air. Cooling efficiency can be reduced, as coolant is not being properly circulated. And over time, the pump can (and will) fail.