Fan effects on HD temperature

[chrisbay90]

I have a little box at home that I use as a home server and do all sort of little fun things with. It lays flat underneath a desk in my office. Very inconspicuous. Except for the two little (60mm) noisy fans i have on the hard drives (one of wich has LED's). So i decided to see if they where at all necessary and thought i would share my results with you.

Take hard drive temperature every hour. Test for 2 days, un-plug fans test for further two days. Compare results. (skip ahead and grab the spreadsheet if you like)

Results: all in degrees C

2x60mm Fan:
Temp range:
HD1: 4, 31-34
HD2: 3, 29-32
Average:
HD1: 33.1
HD2: 30.6
Analysis
Temperatures seems very consistent. There where no spikes, all changes where gradual. There temps flowed uo and down consistently with that night/day ambient. HD2 was on average 3 degrees cooler, but changed in temperature consistently with HD1

No fans:
Temp range:
HD1: 6, 35-41
HD2: 4, 32-36
Average:
HD1: 38.7
HD2: 34.9
Analysis
Very surprising. I was not expecting much of a change and any change to come about gradually. However within 30 mins of removing the fans the temperature spiked exactly 5 degrees on each drive. The temperatures peaked and trowed exactly as they did with a fan, only having a higher average temperature. They did seem ever so slight more susceptible to extremes with a slightly bigger range in temps.

Given these results, the fans undoubtedly do a lot in keeping the drives cool. Given that the fans didn't actually reach HD2 (they blow beneath it, see pic below), was surprising. So I was going to have to reduce my noise another way. I decided to get a larger, quieter fan in the hope of reducing noise and maybe even temperatures further.

Here are the temperature results of a 120mm 57CFM fan.
Temp range:
HD1: 4, 27-31
HD2: 3, 24-27
Average:
HD1: 28.5
HD2: 25.3
Analysis:
Amazing, that's another 5 degree's drop AGAIN (total of 10 degrees compared without fans), within a measly 30 mins of install. Again the drives temperature patterns follow EXACTLY the same characteristics, only with a lower average.

Conclusion.
There you have it. Putting a fan in the front of your case, blowing on to your HD's makes a huge difference in temperature. Much bigger and much more abrupt than I imagines. Wether this actually effects performance or reliability, I can not answer.