1. Introduction2. Testing Methodology and Results3. Discussion and Closing Thoughts4. View All Pages

When I built my first PC a few years back, I used the excellent Cooler Master Hyper 212 EVO to cool the processor. However, I remember feeling very confused about how I should mount the fan to the heatsink – some people said ‘just stick it on any way', while some online pundits were certain that I HAD to use two fans in a push/pull configuration or else my PC would burst into flames at any moment.

I am of course exaggerating slightly, but there is a great deal of misinformation and contradictory statements to be found online about setting up the fan(s) for the CPU cooler. This article is designed to cut through the noise and get to the facts: does it actually matter where you mount your fans, or how many you use? Read on for how I put this to the test, as well as the all-important results and what conclusions can be drawn from the data we gathered.

Testing methodology

To get accurate data from comparing various fan configurations, it was very important I devised a scientific and easily repeatable test. Most importantly, however, any test would have to be relevant to the average consumer – so using a £5,000 custom watercooled PC would not have been the smartest move, for example.

Accordingly, I devised a simple test where the only changing variable was the number of fans used, or how they were mounted. Here's what I did:

First, I built the system for testing in the Kolink Aviator V chassis. This case features three fans out-of-the-box, with two fans intaking at the front of the chassis. This means the components are supplied with a high level of air. In the system I used an Intel i7-5820K, MSI X99A SLI Plus motherboard, 16GB of Panram Ninja V DDR4, a Sapphire R9 285 ITX GPU, an OCZ Trion SSD and a Corsair RM750x PSU.

As for the all-important CPU cooler, I decided to pick two – the Cooler Master Hyper 212 LED air cooler, as well as the Arctic Liquid Freezer 240 all-in-one liquid cooler. This way we can assess whether fan configuration makes much difference whether you are using a radiator or a more typical heatsink tower.

For the Hyper 212 LED, I used CoolerMaster's Air Balance 120mm fans for this test. I used the included F12 fans for the Liquid Freezer 240.

In terms of actual testing, I performed three tests per cooler – obviously testing out push, pull and push/pull fan configurations. To get a temperature reading, I ran Prime 95's (version 26.6) Small FFTs test for 10 minutes before noting down the maximum CPU temperature. I also used an NZXT Grid+ V2 fan controller to lock all the system's fans – CPU and chassis fans – to 50% speed, ensuring PWM control does not influence the testing today.

Results

I must admit I was quite surprised by the results – specifically, by the fact that using extra fans (one extra for the air cooler, two extra for the AIO) in a push/pull configuration made so little difference.

To put it in plain numbers: across both tests, using a push/pull configuration yielded up to a 4 degree reduction in temperatures. In some cases, the difference was 2 degrees. Why is this?

To answer such a question, I cannot give a definite answer, only a few suggestions.

First, I would point out neither the Cooler Master 212 LED or the Arctic Liquid Freezer 240 are the biggest of coolers.

What I mean is, the air being pushed through each cooler does not encounter as much resistance as if I had been using a 60mm-thick radiator, for example. This would mean using any extra fans in push/pull makes little difference as the air is already flowing easily enough, rendering the extra fans redundant.

Another factor could be the fan speed. I set every single fan used in the test system to run at 50% – this way we eliminated any potential interference from the motherboard's PWM controller. However, I would suggest at a lower fan speed – say 25%, for example – using a push/pull configuration may have made a bigger difference. This would be because less air is flowing due to the lesser fan speed, so adding in the extra fan(s) in a push/pull config could have made a bigger impact as it would have increased the amount of air flowing by a significant margin.

However, both those explanations are just educated guesses – I could not confirm anything until I tested both of those hypotheses as well. I would also stress I am not trying to take away from the results – only to explain why the difference is not as big as I thought it would be.

There is also the small caveat that a test like this is hardware-specific, so I cannot guarantee the temperature difference between fan configurations would be the same 4 degrees across all PC systems. That being said, though, I conducted each test in a scientific fashion and the results do not lie – the biggest gain I saw from using a push/pull setup over a pull configuration was just 4 degrees.

Whether or not this 4 degree difference is significant depends on the circumstances. For example, if your CPU peaks at 50 degrees by default, then there would be little point in investing extra cash for fans to run a push/pull configuration. By contrast, if your CPU is much hotter and is getting close to its thermal ceiling, an extra fan or two would go a long way to bringing those temperatures down to a safer level.

Still – as I said, the data cannot lie. As such, the conclusion I would draw from the data is this: unless your CPU's temperatures would really benefit from a 4 degree reduction in temperatures, fan configuration does not matter that much after all.

KitGuru says: In this article I have shown that, in actual fact, fan configuration actually makes little difference. Still, we want to hear from you on this – so sound off in the comments about what cooling setup you have and whether you think it needs any tweaking. Bonus points to anyone who tells us their max temperature under 100% load!

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