This content has moved - please find it at

Although these pages remain accessible, some content may not display correctly in future as the new blog evolves.


Initial thoughts on the Cooler Master Pi Case 40

Today I received a pair of Cooler Master Pi Case 40 cases, a Kickstarter project I backed in July. It has actually been available for purchase from other retailers for some time whilst backers such as myself cooled our collective heels.

This case is a passively cooled aluminium case for the Raspberry Pi 4 that also features a programmable button (e.g. for switching it on an off). It is also supposed to include the STL files so that alternative parts can be printed, although I don't think these are available yet.

These are my initial thoughts for the case, less than a review, but more than a quick judgement.


The outer packaging

I really like the packaging. It is a snug and unassuming box, inside of which is the case, four screws plus the Allen key required for them, and four VESA mounting brackets (sans screws). There are also two thermal pads, although as the case only directly touches one chip I'm not sure why two are provided.

Installation instructions are printed on the insides of the box. All in all, it is a really neat package.


The top of the assembled case

The first thing I noted when I took the case out of the box was that it was missing the Cooler Master logo - there is a silver shield in the right shape but without the logo itself. Not sure if that is by design or not. It has a nice compact size to it - only slightly larger than the Pi itself, and much smaller than the Argon ONE from my previous review.

The case is comprised of three pieces, a smokey translucent base, an aluminium upper, and a rubber bumper around the sides. The top features a button that you are able to program for rebooting or shutting down the Pi.

The inside of the case and the base

The inside of the case with a Raspberry Pi 4 fitted

Just like the Argon, the Pi Case 40 redirects the GPIO ports, this time to the side of the device. The rubber bumper folds back to allow access.

The base has two rubber strips which help prevent the case from sliding. One of these strips is slightly offset from the edge of the case to allow space for the screw holes (see section on VESA below). This is unfortunate as the programmable button happens to be on this side of the case, meaning when you press it, the case tilts and lifts off the surface.

The base of the case along with the mounting arms

Incidentally, the screw holes line up with the holes in the Pi itself and so it all screws tightly together.

The thick section in the top of the above photo is a rubber cover over the SD slot. Just like the GPIO cover, this peels back to allow you to swap out the SD card easily.


The case is actually a really nice package. Aside from the rocking when pressing the power button, the design seems really nice - the bumper means if you drop it it is less likely to get damaged, the plastic base isn't ugly and as it is translucent, you can see the power and activity LEDs of your device.

The side of the case showing activity LEDs and also a slot for ribbon cables

But here is the thing (aside from the fact that they started selling the case on other sites before the backers ever got their hands on it). If you use a Raspberry Pi, it's quite likely you'll want to make use of the GPIO ports. For example, to plug in an external sound board. I bought two of these cases as I wanted to upgrade both my Kodi and Mopidy devices, the latter using a pHAT BEAT.

Except, for reasons known only to Cooler Master, they reversed the GPIO rows so you cannot use any hats with the device!

The Pi Case 40 alongside the Argon ONE. The GPIO rows are the wrong way around

Their statement after previously claiming it was a labelling error and would be fixed in the final product was

Pi Case 40 is designed for the On-The-Go Raspberry Pi users searching for a reliable, durable, and compact solution that suits their nomad lifestyle.

The focus is on Thermal Performance, Durability, and Portability while keeping full access to the board's connectors.

Please note that Pi Case 40 is not meant to be used together with HATS and other accessories that require connection to (or part of) the standard GPIO of the Raspberry Pi 4.

This, together with our plans on developing a new top panel with full hats compatibility, has been shared and communicated multiple times.

This is unmitigated poppycock. If this was the case, then they may not have exposed them at all - and certainly wouldn't have said it was an error that would be fixed. Not to mention... VESA mounts for an "on-the-go" user?

I don't know if they just screwed up and didn't realise until it was too late, but this excuse is a poor one and makes at least one of the cases completely useless to me without modification.

Who in their right minds would design a case for a Raspberry Pi that wasn't compatible with a Raspberry Pi?

As far as I'm aware, that statement was also the first time they communicated this, bar an original comment where they stated it was an error that would be fixed. And if they do fix it I'm willing to bet they will ignore their backers who put misplaced faith into this project.

Finally, their own product pages don't even make note of this fairly important fact which also seems a touch suspicious.

Thermal Qualities

I have left the Pi running as I write this review. It is a fresh install, no extra software and the Pi is just sitting at the desktop with the Pi Tool software open. It has been constantly at 42°C and the top of the case is warm to the touch.

It seems no better or worse than using the Argon. However, I haven't done any extensive tests.

With that said, after dismantling my case in preparation for putting it back in the Argon, I realised I didn't take a screenshot or photo of the Pi Tool, so I plugged it back in. In its bare state, the temperature of the Pi rapidly rose to 57°C with the Pi Tool open. Closed, it dropped to 50°C. So clearly the aluminium case is working to passively cool the device.


In order to use the programmable button, you need to install Cooler Master's Pi Tool, which is accessible from their GitHub repository.

The Pi Tool software

This 300MB+ tool includes some nice charts of system load and can enable overclocking, all of which in all honestly I think is completely pointless.

Frivolous features aside, it does let you configure the button mappings for sequences of long and/or short presses. I did notice some oddity though - after restarting, the button mappings had reset to the default value of "off" and had lost my short press binding. Later on when booting up again to take the above photo I noted that the long press binding was back to "on", although my short press binding was still missing. So there seems to be some sort of issue with the software.

When testing the button, unlike the Argon, there was no immediate action. Each time I tested the long or short press, there was a delay before the Pi shutdown or rebooted, each time long enough for me to think it wasn't working.

Oh yes, and if you answer "Yes" to "Install Desktop Customisation", which I naturally assumed was a "Do you want to install the Pi Tool", it changes your desktop wallpaper to a Cooler Master branded image.

No, I didn't actually want you to change my wallpaper

VESA Mounts

One of the nice features of this case is that it comes with four plastic arms you can use to mount the case on televisions or monitors which support the VESA standard. There are 3 notches next to each screw hole on the base so that you can orient them to fit various different sizes. I tested this with an ancient spare monitor and although I didn't have screws of the right length to hand, it clearly worked fine which should be useful for the case I will use with the Kodi (after I find more appropriate screws!).

Temporarily mounted on a truly ancient monitor


  • Provides passive cooling for a Raspberry Pi
  • Sturdy case which looks like it can take a tumble without damaging the Pi
  • Power button!
  • Mounting arms
  • Ribbon cable access


  • Hats cannot be used
  • Due to the case acting as a heat sink, it could get very hot
  • Pi Tool software seems to forget button mappings
  • Pressing the power button seems to have some form of lag before it executes

Closing Thoughts

If your intended use for a Raspberry Pi does not involve using hats then this is a serviceable case.

I do not recommend this case. Frankly, I don't recommend Cooler Master and will not buy their products again.

About The Author


The founder of Cyotek, Richard enjoys creating new blog content for the site. Much more though, he likes to develop programs, and can often found writing reams of code. A long term gamer, he has aspirations in one day creating an epic video game. Until that time, he is mostly content with adding new bugs to WebCopy and the other Cyotek products.

Leave a Comment

While we appreciate comments from our users, please follow our posting guidelines. Have you tried the Cyotek Forums for support from Cyotek and the community?

Styling with Markdown is supported



# Reply

Good to hear that I'm not the only one having issues with button mappings using the pi tool haha! However in my case it happens very consistently every time I launch kodi, which makes it pointless really since if I want to use the button to shut down I have to exit kodi, open pi tool, and re-enable the mapping. And for the life of me I cannot figure out why this happens (I'm not all that tech savvy).