Mac Mini Cooler Prototype

Now that i've been running my new Mac Mini for a week or so I have been testing it and stressing it to see what its capable of. It seems pretty happy transcoding 3 1080p H.265 streams at once but it does spin up the fan to full speed and maxes out at about 95c CPU core temp. I want to remedy this, one way would be to move the Mini to somewhere else in the house where it would get cooler air or just more airflow. However i can't do that at the moment.

I'm going to try make a cooling plinth for the Mac to sit on, I have a couple of new 120mm fans i can cannibalise to come up with something.

120mm Fan.

120mm Fan.

USB lead wired in.

USB lead wired in.

The underside

The underside

First step was to modify a fan to see if it was likely to work properly. The fan spec states 12V @ 300mA however i intend to run it from a standard 5V USB socket. Ohms law states that voltage is proportional to current. So with a bit of math: 0.3A/12 gives us 0.025A per volt, times that by 5V = 125mA. 5V*0.125A = 0.625W, so well within the power spec of USB. I soldered a USB lead directly to the fan and it works. Its turns slow enough to be silent but is big enough to produce decent airflow.

The modified fan.

The modified fan.

After that i cut the fan from its frame, i used a stanley knife, coping and jewellers saw to cut and shave the tough glass reinforced plastic shell. 

To my surprise a 120mm computer fan is more like 110mm (blade diameter). This is a stroke of good fortune as i happen to own a 114mm hole-saw that i bought for running some extractor fan ducting some time ago.

Glued into the hole with a little contact adhesive ..

Glued into the hole with a little contact adhesive ..

Felt feet to space it off the deck.

Felt feet to space it off the deck.

I cut a hole in a piece of chipboard for the base, this will be sufficient to test my idea. The Mini will sit directly on top of it, having air pushed into its intake. I spaced it off the floor with some felt spacers to allow the fan to suck air from underneath.

I'll test the idea over the next few days.

I prayed for twenty years but received no answer until I prayed with my legs.
— Frederick Douglass