MiniPC passive cooling – T-Bao MN35 and Derivatives

The Mission:

I have found the MiniPC described here under the following brand names at Aliexpress and Banggood:

  • T-Bao TBOOK MN35 AMD Ryzen,
  • Chatreey AMD Ryzen Mini PC,
  • TOPTON Günstigste Mini Pc.

    The computers are all identical in construction but differ according to equipment with CPU, Ram, SSD und Preis.

For testing purposes, I ordered 2x the T-Bao MN35 with Ryzen 5 3550H and 1x the Chatreey AMD R7 2700U. Both types run with 4 cores and 8 threads. You can find detailed tests on Youtube. I don’t want to go into detail about what they can or can’t do, but only how to convert them.
But I can say this much: for the operation of a small home server running Proxmox or my solution with X2go, the PCs are absolutely sufficient. Here, at least three VMs are constantly running at the same time (2x Linux + 1x Windows 10) and that doesn’t really scratch them.

Let’s get started….

This is needed:

  • Some craftsmanship + tools that many should have at home.
  • Cooler: ARCTIC Alpine AM4 Passive for around 15€
  • hacksaw (hand)
  • hammer / sledgehammer
  • pin driver, alternatively something sharp, durable metal e.g. an old, defective screwdriver
  • metal file
  • 40 grit sandpaper
  • Phillips screwdriver in different sizes
  • thermal paste
  • heat conductive glue, optional but recommended
  • Mini WLAN antenna (2.4+5GhZ)
  • RP-SMA IPEX cable for the antenna connection
  • 3mm + 6.2mm metal drill bit
  • drill/accumulator screwdriver
  • Vise
  • Alcohol or similar to remove thermal paste and grease

Step 1, Disassemble PC:

No, do not immediately reach for the hammer 🙂
At the bottom of the housing there are 4 Phillips screws, by removing them the housing, which consists of a top and bottom shell, is opened and the entire PCB is removed.

We carefully detach the WLAN antenna, which only consists of a simple cable, from the lid so that there is more freedom to work.
Then we loosen the four screws that hold the heatsink in place and remove it with the fan screwed on.

Step 2, off to the workshop:

Now the retaining pins to which the fan was previously attached are knocked out of the heat sink with the help of a cotter pin driver. The pins are simply pressed into the metal and require a strong blow.

Important !!! Leave the welded sleeves with thread alone, we need to screw the radiator back on.

Now we get rid of the cooling fins (better pictures will follow).
To do this, we carefully clamp the heatsink (aluminum) on edge in a vice and slowly but surely saw the fins off the heatsink.
This way we degrade the heatsink to a holder for the upcoming passive cooler.

Since the upcoming cooler should have as much contact surface as possible, we now have to grind the plate as flat as possible. This sounds wilder than it is, since aluminum is quite easy to machine. The surface does not have to be 100%. The important thing here is that the plate is as flat as possible, without any rough edges and is not bent by the vice.

The board must now be cleaned and degreased with some pure alcohol, brake cleaner or similar. Then we screw it back into our MiniPC.

The next step is optional and involves attaching a wifi antenna to the outside of the case. The existing cable antenna can of course simply be glued to the side of the heat sink or similar. Of course, mounting a „real“ antenna is nicer.
For this, a hole is drilled on one side of the case, the antenna is screwed on and wired. When wiring, make sure that the cables are routed as quickly as possible from the bottom side of the board to the top side, because the components on the bottom side can impair the reception very much. So if possible change the side where the wlan card is located or pull the cable through !!!!

Attention !!! In the following pictures I have laid the cable exactly wrong and had almost no wifi reception.

The old cooling paste of the processor is removed, new one is applied and the plate is screwed on again.

The heat sink is provided with thermal paste and placed on the plate. Here you can work with adhesive conductive paste, so that the heat sink can no longer move. Of course, it would be nicer if the cooler was screwed on somehow, but I didn’t care because the cooling is still very good and absolutely silent.
Screwing the Arctic Cooler could be done by drilling directly through the plate, drilling into the cooler and cutting threads there, but that was too much work for me.
I also left out the top of the case because it increases the cooling performance and the components on the bottom, especially the SSD and Ram, are cooled better. The lid can also be cut out with a Dremel if you want to mount it again.

If the cooling is not enough, because you are baked under the old building roof in the summer like me, you can use a 120mm USB fan for the time very nicely and operate it on the LOW level. It is much quieter than the built-in fan.
To be prepared for any case, I have installed a Noctua NH-L9a-AM4 (black) in my server (instructions follow), which is active but still under no load even remotely audible and I am very sensitive to noise. Computers that are used for daily work must not be audible to me and that’s exactly what my „little punk“ fulfills to the fullest satisfaction.


Temperatures:

The room temperature during my measurements was 28 degrees, since I live under the roof. This should be kept in mind when looking at the measured values, since the values would naturally be corrected downwards at normal room temperatures of around 20 degrees.
However, I found such a „summer test“ exactly suitable to test a passively cooled system.
A CPU stress test with CPU-Z, in which all 8 threads of the processor were under full load for over 30 minutes, brought a maximum temperature of 82.6 degrees Celsius. Of course, this has little to do with the standard loads of a CPU, because the temperature fluctuates between about 45 and 70 degrees Celsius during normal work.
I haven’t been able to cause throttling yet, no matter how hard I tried, the CPU would theoretically shut down at 95 degrees Celsius, so there’s still room for improvement.
During the stress test, I measured 52 degrees at the lower end of the cooling fins and 46 degrees on the outside with a laser thermometer, which is quite sporty but neither critical nor dangerous.
The cooler heats up to about 35-40 degrees on the upper side (end of the cooling fins) in normal operation, so it gets about lukewarm.

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