Tao of Mac

Oct 27th 2024 · 3 min read · #cooling #copper #heatsink #radxa #sbc #x4

Making the Radxa X4 Even Cooler

Back , I went to some trouble to go over its thermal characteristics and how well that massive heatsink worked.

At the time, I resorted to using my own thermal pad to get the best possible contact between the CPU and the heatsink, but apparently that was not enough, because the board still ran a bit hot under load.

This weekend I decided to do something about that–I took one of the SSD copper heatsinks I had lying around, verified that it was thin enough (it was exactly 1mm), cut it to match the heatsink contact plate, and applied some thermal paste:

Copper shim in place
Checking the shim size after cutting. I also padded out the VRM "trench" to ensure they had some cooling.

And behold, the X4 booted to a nice, cool 28°C:

# sensors
coretemp-isa-0000
Adapter: ISA adapter
Package id 0:  +28.0°C  (high = +105.0°C, crit = +105.0°C)
Core 0:        +29.0°C  (high = +105.0°C, crit = +105.0°C)
Core 1:        +29.0°C  (high = +105.0°C, crit = +105.0°C)
Core 2:        +29.0°C  (high = +105.0°C, crit = +105.0°C)
Core 3:        +29.0°C  (high = +105.0°C, crit = +105.0°C)

To verify that this was not a fluke, I ran the same load test I had used in my original review, and the temperatures peaked at 48°C, staying well below the 96°C I got last time:

temperature chart
A vastly improved result over the initial benchmark

Even better, the board had a steadier CPU boost to 3GHz at the start, and held up nicely at 2.5GHz for the duration of the test, without the slight throttling I had observed before:

MHz chart
Average MHz across cores

I’m quite pleased with these results, and I’m going to leave the shim in place to (finally) do some testing with Windows. It’s a simple, effective solution that doesn’t require any permanent modifications to the board, and it seems to work quite well.

Caveats

I should note that the original testing was done in August and at higher ambient temperatures (but, according to my office thermometer, by only about 4°C), but even then the difference is quite noticeable. I’m not sure if the thermal pad I used was sub-par (it was what I had on hand that bridged the pretty wide gap between the X4’s CPU and the heatsink), but the shim definitely seems to have done the trick.

Also, I kept the heatsink fan, but I’m not sure it’s even necessary anymore. I’ll have to do some more testing to see if it makes a difference in practice (I suspect it will, but I’m not sure how much).