I needed a cheap heatsink for my Raspberry Pi 3 that I use as a music player/server. To maximise performance, I wanted to overclock the computer for faster searching and handling of all my music. I’ve managed to overclock my main Stratum-1 NTP server to 1350MHz without any problems, but the dinky little aluminum heatsink was way to anaemic so I found a very cheap DIY solution to my problem. With this heatsink I can run the Raspberry Pi 3 at 1.5GHz all day at full tilt without any problems!
When it comes to heat dissipation, there’s no substitute for size and the right material. Copper is heavy and has excellent heat transfer abilities, so I searched and found cheap GPU heatsink shims that was 15×15 mm for under $8 including shipping. All I needed to do was to stack a lot of them on top of each other, while having them protrude on each side for heat dissipation as you can see on the picture. A good side effect is that the heat sink isn’t high, so I can have my DAC-card mounted without a clearance problem. So I got some cheap heatsink compound and regular super glue and just put the heat sink compound on each copper plate, leaving space in the middle for a small dab of glue. Yes, I super glued the copper plates directly on the CPU, because, hey, a Raspberry Pi is cheap!
And the results are great!
This is the settings in /boot/config.txt for the overclocking part.
temp_limit=85 #Will throttle to default clock speed if hit.
Running the command
sysbench --num-threads=4 --test=cpu --cpu-max-prime=2000000 run
for over an hour, the temperature never exceeds 65 C° and this while at the same time playing 24-bit 192KHz audio. This is a Raspberry Pi 3 mounted inside a box with a DAC card added on top! I’ve waited two month before writing this up, because I wanted to make sure it would work in the long run. It’s now been running continuously now without any glitches. So the next step is to try the same thing on my NTP server. That Raspberry Pi 3 is mounted in my 3D printed box with a fan, so it’s going to be interesting to find out if I can go higher than 1350MHz that it’s currently running at. Hoping for 1.5GHz on this one as well naturally…
Doing More Useful Stuff…
A commenter mentioned that doing a kernel compile would simulate hard use of the Raspberry Pi 3 better, so I downloaded the source code and did two compiles after each other of the complete kernel. Highest temperature? 66.6°C or 150,8F. Must be working with a daemon that made it come up with that number.
I was just a bit curious how much current the Raspberry Pi 3 would draw, because I have a 5 Volt, 1 Ampere power supply and there’s a lot of talk of needing 2 Ampere. Using my beloved YZXstudio USB Power Meter to my surprise it only used around 560 milliAmpere, using up about 2.8 watts. This is with 100% usage on all four cores. This is without the DAC running though. I had to double-check that number, because I thought it would be much higher, but it’s correct. Nothing connected to the USB ports helps probably and no screen. But pretty good!
Maybe I just got lucky with this card, and it’s a fluke, because there are differences between cards. But I think this is an excellent alternative to the cheap aluminium heat sinks that everyone is selling anyway.