Does a cool Raspberry Pi 3 run more efficiently?

Question

I think this is a slightly different question related to hardware temperatures. I am curious about the drop in temperature after adding a fan and the impact of temperature on processor efficiency.

I am in the process of building a Raspberry Pi 3 cluster. Only 3 nodes so far, but I hope to use it to learn and crunch numbers for SETI@Home.

With all three boards running the BOINC client at maximum capacity, here are the temps I'm seeing with vcgencmd measure_temp:

Rasp1 = 82.2 C

Rasp2 = 73.6 C

Rasp3 = 70.9 C

As a test, I took a regular house fan and ran it on the cluster on high for 15 minutes. I checked temps again:

Rasp1 = 47.2

Rasp2 = 43.5

Rasp3 = 42.9

Here's my question, will the cooler cluster run more efficiently and perhaps process at a faster rate?

I may invest in a smaller fan designed for the job to keep these boards as cool as possible.

Appreciate any thoughts or feedback!

Answer 1

As discussed here What's the maximum / minimum running temperature? and taken right from the official FAQ:

What is the usable temperature range?

The Raspberry Pi is built from commercial chips which are qualified to different temperature ranges; the LAN9512 is specified by the manufacturers being qualified from 0°C to 70°C, while the AP is qualified from -40°C to 85°C. You may well find that the board will work outside those temperatures, but we’re not qualifying the board itself to these extremes.

But that is only half the answer here as the question also addresses whether "the cooler cluster [will] run more efficiently and perhaps process at a faster rate?". And the answer to this is yes, running at elevated temperature leads to thermal throttling - a reduction of the systems frequency to reduce the thermal load. So while cooling does not increase computational power it prevents the reduction for overheated systems.

This blog post finds a reduction of clock speed above a system temperature of 85°C.

Fully enclosed in the case the temperature climbed quickly and four minutes into the test the Pi began to under clock gradually to maintain a temperature under 85°C. The Pi reached a peak temperature of 84.2°C and the minimum reported clock speed was 851MHz

So keeping the Pi within operational temperatures (if need be by heat spreaders or fans) may prevent thermal throttling and thus avoids reduced computational power due to reduced clock speed.