AiO watercoolings are without question very popular and offer beside a good cooling performance and a great optic also the possibilities for a flexible mounting of the radiator. However, this raises the question: where to put the radiator for the best airflow? Mount it in the lid and convey through it the hot air of the graphics card, or better into the front of the case, where then, however, the GPU can start to sweat? In which direction should promote thereby the fans in each case?
Using the Fractal Design Define 7 Compact (review) as an example, we tried out the variants and looked at how to find the best balance and how to optimize the effects with additional fans and combine the advantages.
For our test, we load both the CPU and the graphics card of the test system. The CPU is loaded with prime95 12k and 8 threads and the GPU with Furmark. All fans were fixed at 1000 rpm for the test. As case fan we use the Arctic P12 PWM PST (at amazon)*, as radiator fan the be quiet! Silent Wings 3 PWM (at amazon)*. It should be noted that depending on the waste heat of the CPU and GPU, the tendencies can shift more towards one component or another.
If you haven’t yet decided on an AiO water cooling system, take a look at our guide and AiO water cooling system test with 12 AiO water cooling systems in comparison.
Positioning AiO water cooling perfectly
As a starting point we take the classic setup with the radiator in the lid and the standard ventilation of the case with a front fan and a rear fan.
Starting position AiO in the cap
Radiator in the lid
With the AiO radiator in the lid, the water cooling also serves for general heat dissipation from the case. If the graphics card is active, the CPU temperature will also increase. In this case, AiO water cooling behaves like an air cooler.
To mitigate this effect, additional front fans should be installed. With this you can reduce the CPU somewhat and the GPU temperature more significantly.
AiO in the lid Optimal
Turn tail fan around
Blow in the lid
The idea to turn the rear fan and thus bring fresh air to the radiator should be discarded immediately. This measure leads to a significant increase in temperature on both components! Also letting the radiator fans blow in the lid is counterproductive for all components.
Radiator in the front
Hoses down or up?
First we must express here a referenceMounting an AiO radiator in the front with the connections/hoses facing upwards is not optimal and needs some observation. In fact, the radiator serves as an equalizing tank in which the air in the circuit collects. If the fill level is no longer sufficient from the factory or over time, the pump can draw air. This manifests itself first as a loss of power to a defect when the pump runs dry! Therefore, it is best to mount the radiator with the connections facing downwards, but in any case overhang the pump. The pump should therefore not be the highest points. Otherwise, the filling quantity should be consistently observed and ensured (if possible).
For practical reasons, we handled this differently for the short test period (tubes below).
If you move the radiator from the lid to the front without retrofitting more fans, you get the picture that was to be expected: The CPU cools down significantly, while the GPU gets all the warmer.
Radiator in the front
Radiator in front with ceiling fan
The best temperatures with an AiO
Already with a ceiling fan you can counter this effectively and lower the GPU temperature significantly. With a second ceiling fan, even both components become significantly cooler and you get the best temperatures.
Conclusion and recommendation for installation direction
The decision when installing an AiO water cooling system between lid vs. Front is simple in terms of temperatures: If you are willing to invest in ceiling fans, front mounting is the best option. If not, the variant is not recommended, since the GPU temperatures worsen massively.
In addition, there is the further problem of air in the AiO. In the long run the typical front mounting with hose connections to the top is to be seen critically, since pump/cooler can draw air. Depending on the housing and components, mounting with the hoses down is not always possible, but definitely the better choice. In any case, the pump should not be the highest point in the system!
AiO mounting in the lid is much easier. Even without additional fans, you are already close to the optimum there and can only fine-tune the temperatures. You also avoid potential problems, which is why we recommend the classic variant.
Recommended fans for AiO water cooling
AiO water cooling poses a certain challenge to the fans due to its high fin density. Following our recommendations for AiO fans
120mm fan without RGB:
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*: In our opinion, the expensive fan is currently the best radiator fan in 120mm format. Price and color scheme are a hurdle *: Almost on par, but significantly cheaper. Can have too at high speeds now and then to a noticeable acoustics
120mm fan with RGB
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* (amazon): Very high performance and appealing RGB lighting for a comparatively low price *: Powerful all-rounder with elegant lighting. Pull mode a bit louder.
140mm fan
Arctic P14 PWM (at amazon)* : Very strong radiator fan for little money, without lighting.
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