The Big Air Cooling Investigation

Written by Paul Goodhead

February 10, 2012 | 08:13

Tags: #air-cooling #case #case-fans #fan #investigation #temperatures

Companies: #bit-tech

Cooling with Five Fans

Stepping up to five fans again sees the law of diminishing returns rear its head - the benefits of using five fans over four are minimal. We only saw differences in the range of 1-2oC which is a relatively poor return for the £10 or so a fan is likely to cost and the extra noise it’s likely to generate.

Again, we also saw that the majority of the benefit was concentrated on the lower end of our graph meaning that the variations across the setups were now very minimal with only one or two degrees difference between the best and worst performing setups.

Five Fans

Arranged by CPU Delta T

  • Front (U), Front (L), Rear, Roof (B), Side
  • Front (U), Front (L), Rear, Roof (B), Floor
  • Front (U), Rear, Roof (B), Side, Floor
  • Front (U), Front (L), Rear, Side, Floor
  • Front (U), Front (L), Roof (B), Side, Floor
    • 44
    • 46
    • 18
    • 44
    • 46
    • 19
    • 44
    • 49
    • 18
    • 45
    • 45
    • 18
    • 46
    • 45
    • 19
°C, lower is better
  • CPU
  • GPU
  • Chipset

This homogeneity makes drawing any firm conclusions from the above graph challenging, but there are still a couple of things we can take away from it.

The first is that when you get to this level of fans you’re best off sticking to the traditional front to back cooling setup. The three worst performing setups each had the side and floor fan installed, which are the two fans that sit most awkwardly with the front to back cooling method as they push air perpendicular to this direction.

This leads to the front to back airflow getting disrupted and being less effective - instead of a nice steady procession through the case the air instead gets into a fight around the graphics card and chipset coolers as it’s pulled in different directions.

Fitting more than three fans to a case can give you headaches in terms of cabling too

Fitting more than three fans to a case can give
you headaches in terms of cabling too

The second thing to take away from the above graph is the seemingly irregular GPU reading of 49oC for the Front (U), Rear, Roof (B), Side, Floor setup.

At first glance this looks like an anomalous result but closer inspection shows that it’s the only setup without a pair of front intake fans.

What this indicates is that with a floor and side panel fan installed you really need the power of a pair of front intakes to push cool air through, into the area of the graphics card.

Otherwise the floor and side intake combine to effectively cut off the graphics card. This isn’t the end of the world - the side panel fan is pushing air almost directly at the card after all, but it’s a less effective setup than including the graphics card in the front to back air flow.
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