So i went ahead and bought a Pi 4 and an enclosure separate. (Newegg didn't have the Pi 400 and didn't want to make a second purchase at a second site, may get the Pi 400 later).

The Pi 4 looks no bigger then a deck of cards. Literally that's what i thought when i saw the box. I can see why so many people make retro handheld game systems from them.

Seems the Pi 4 is the first in the pi series that needs active cooling; Pi 1-3 are a little slower but were more like the original 8bit systems where the chip ran naked. The Pi 4 needs at least heat sinks, say either a big one, or small ones plus plenty of air or a small fan. Pluged in a tiny fan into pins 1 & 6 and you get 3.3v enough to keep it cool.

Anyways, it feels like it runs like a 2015 laptop, except with much better video playback due to hardware support. The default Pi OS is still 32bit so if you get the 8gb you are likely missing on features. But getting different images for the OS isn't hard.

The little machine does seem to do the job, now for listening to news, music, or watching anime, chatting and email i don't need the Roku, or my big beefy gaming rig. The 90% uses people need for a system.

If by active cooling you mean fan(s), not necessarily, at least if you don't overclock it.

I originally bought for my 4GB RPi4 some cheapo acrylic plastic case which had one small fan (no heat sink). It kept the RPi4 pretty cool but I didn't like the high-pitched fan sound as I keep my RPi4 running 24/7.

After some months the fan stopped working, I suspect due to dust jamming it. Dusting it off didn't make it work. I replaced it with the Flirc case which has no fans but is made of aluminum and basically acts as one big heatsink for the RPi4 CPU. You can feel it when you touch the case under heavy load, it can feel quite warm, even hot. The heat dissipates quite well from the whole case.

If you are looking for a silent case for RPi4, I recommend the Flirc case, or some similar aluminum case. Also since there is no active air flow, it will not accumulate dust inside the unit either. (With my earlier plastic fan case, I had pointed the fan to blow air out, not in, hoping that would prevent dust accumulation inside the case somewhat.)

I rarely see the CPU temp go over 60 Celsius degrees with the Flirc case even under relatively heavy load, maybe the highest I recall seeing is little over 70 C. Without a case/fan it could easily go well over 80 C under moderate load, after which the CPU starts to throttle in order not to overheat.

https://www.amazon.com/Flirc-Raspberry-Pi-Case-Silver/dp/B07WG4DW52

EDIT: This raises the question though, how good is the cooling in the RPi 400? The "case" (keyboard) is apparently plastic so does it have any fans and/or additional heatsinks?

I have just recently started experimenting with the 64bit alternatives, both the beta Raspberry OS (64bit) and Manjaro RPi. I've upgraded the RPi4 firmware/bootloader to the latest version so that it allows also booting from USB devices, in case there is no SD card inserted in the unit. This way I can easily experiment with different RPi OSes by just booting from different USB devices (USB HDDs, USB memory sticks or whatever). Naturally you can also have several SD cards which you keep changing, if you are so inclined.

The little I have tried:

64bit Raspberry Pi OS:

This is in beta. Generally it seems to work ok, but for now I've decided not to use it primarily due to:

- Apparently it doesn't yet support hardware video acceleration on VLC and Chromium like the 32bit does. This is important for me as I use my RPi4 also as a media play box.

- Some software that is important to me doesn't apparently yet run on 64bit Raspberry Pi OS, like AnyDesk (= TeamViewer like remote desktop software). According to some discussions it has some dependency problems in 64bit and the developer would have to start supporting the 64bit OS.

Manjaro ARM:

- Generally it seems to work ok, but I have an odd problem that sometimes the OS becomes unresponsive and e.g. all the icons become as if "broken links".

I suspect the reason for this is that the USB hard drive (or the USB dock station where I have the HDD) goes to sleep mode when inactive for some time. I am unsure if I should change some setting within Manjaro (so that USB ports never go to sleep?) or if this a feature in the USB HDD dock station that I am using, or some other thing... I don't recall seeing this issue with the 64bit Rasp OS running on the same dock station, but maybe I didn't use it long enough.

Maybe I could retry by installing Manjaro either on a SD card or USB memory stick and see if the issue happens there too.

Mhmm. I'm sure CPU throttling is done on a hardware level, when under a heavy load. Not sure about the case thing, since the case i have has a lot of room, so it's not like a bunch of heat is building up, plus the fan is like 1 inch away from the board running at 3.3v. Still i'm hesitant when i see it pushing 80. When not running that intensively it's usually 60.


Yeah those would be hard sells.

Been using this distro for a few days. It works, though i'm not used to using the software manager and kinda prefer apt at this point.

I've never seen the system show broken links, so sleeping drive does seem suspect. I'd say take the minimum size SD card you can get and put the OS on it, and then link everything that isn't core OS related on the external. Not quite best of both worlds.

Though i have done Squashfs and compressed and mounted the /usr directory using gzip/lz4 and it seems to run the programs and system faster. Could be due to limited bandwidth from the card that the decompression is faster. xz on the other hand slows it down to the same speed so unless you are super space limited i would avoid it. I'll experiment with getting unionfs running with it so changes are allowed and persistent.

Can't help but feel slightly fed up with Manjaro. Overall it works. Just a few nitpicks that i am not sure how to change yet.

It's just passive cooling. The keyboard shell may be plastic, but it has a big ole aluminum plate as a cooling device (as well as acting as an electrical shield and giving a bit more heft to the the device). Tom's Hardware did a nice temperature comparison of regular RPi 4 vs 400 in their review. Even at a max overclock to ~2.2Ghz (from the normal 1.8), the 400 still ran cooler than the stock 4 at its 1.5Ghz level.

How does zstd compare?

Good question. I'll get back with you after i compress it and reboot using it mounted.

edit:
Alright, so results...

Algo, Orig -> New Size, Notes
Gzip/lz4 5Gb -> 1.9G, fast decode
xz 5Gb -> 1G, slow, maybe slightly slower than the SD card
zstd 5Gb -> 1.2G, (22 level compression). Not sure, zstd not supported error message.

xz is suppose to have a BCJ filter which compresses executables better by being a 'lossy' compression of some distinction, likely changing certain calls to other types that's easier to compress. Not sure if that will slow them down or just make them easier to compress and decode initially. Not sure. In IRC clever tested it, took 2x longer to compress, and saved only 100Mb (8.5Gb originally, so from 2.7G to 2.6G from his system)

Yeah I think the throttling is done on a hardware level, I don't recall exactly but doesn't it start throttling if the CPU temps go over 85C or something?

I recall I was able to reach those "above 80C" temperatures under heavy load (not overclocked) quite easily when the board was sitting bare without heatsinks, cases or fans.

Right now with the passive-cooling Flirc case, the overall CPU usage is at around 80% all the time and the CPU temps are at around 62 Celsius degrees, which sounds very nice to me considering it is totally silent without a fan. The room temperature where the RPi4 is is around 23C or so.

Things that I am running right now to cause that 80% CPU usage:
- two instances of gogrepoc.py (a python script), one is downloading my GOG game installers and the other is running MD5 integrity verification for some of my already downloaded GOG game installers.
- AMule running in the background (downloading some rare files that take a long time to download from the ed2k/Kad network)
- AnyDesk (remote desktop application) is active, as I am currerntly connected to the Raspberry from this PC to the RPi4 with it.
...and whatever RPi4 itself is running in the background of course.

EDIT: Oh and mount.ntfs is using quite a lot of CPU resources as well, since those two 2.5" USB HDDs that have my GOG game installers and are now connected to my RPi4 are formatted with NTFS (so that I can easily access them in Windows of course).

Yeah there could be something in the dock station itself, even that is has issues with USB3 ports as I recall it having some such issues also on my Windows laptop if I connected to a USB3 port (ie. especially under heavy data transfers, sometimes Windows would just go "oh there's no drive there, disconnected... oh there it is again!". Could be the USB3 cable even. Maybe I try it on the RPi4 USB2 port, even if that will much slower (but then running the OS from a SD card is quite slow too I guess...).

I guess I could also run the core OS from the SD card, that is how the original 32bit Raspberry OS is set up right now, ie. the /boot is in the SD card but / (ie. everything else) is in the external USB HDD. That setup has certainly worked fine so far.

85 is the max working temperature before you have serious chip damage. It is suppose to start throttling at 80 degrees. I've seen on my monitor in the corner say up to 82, but it usually dips back down, i'm just a little worried about harming my pi. So i sometimes will Ctrl+Z my process (pause it) and let it go back to 65.

Although i've also changed how many threads it generates so 1 core tries to be free to cool down from xargs and that worked decently enough.

Hmmm... I'd be tempted to have a mounted instance of the SD with major files and directories as a backup, and then softlink them to the SD. Though i'd really consider /bin /sbin /usr/bin /usr/sbin /lib /usr/lib to be main directories you always want access to. (I hope that's all of them)

At least on the 4B, if the temperature gets high enough to throttle, you will see a blinking thermometer at the upper right corner of the screen. At 80, it will appear, and it will blink faster at 85.

(Supposedly, the cooling is better on the 400 than on the 4B.)

I actually saw that indicator on the Pi OS once. Which made me tear mine open to salvage a fan and add extra cooling rather than just heat sinks.

The 400 has a HUGE heatsink that spans the entire keyboard length; at least that's what was shown on a teardown in one video.

I believe that indicator is actually from the firmware, not the OS.

I'll disagree, I DID see it on the Pi OS however so i can verify that does pop up. However using Manjaro i've hit 82 before and not seen the indicator.

Well i found a good use for my Pi4. It's been sitting in a box untouched for over a year (since i moved).

But i've been wanting to not use my main system much as for how much power it takes vs other things, plus being in different rooms. So i installed Lakka. Lakka is a variant of LibRetro/RetroArch, and with a 32Gb microSD i have i can load a lot of old memories of games i have laying around.

What's most surprising is the interface looks like a PS3... But with the Vilros controllers and case, and a little configuration per-game I've managed to get quite a few things up and running just fine.

What's more disappointing is what doesn't work (PS2). Still, it's generally working so far.

What to expect from the Pi4, you can get any 8/16bit emulation working probably just fine. NES/Genesis/SNES/PS1/Apple/Atari etc. Handheld consoles will probably work too.

What probably won't work, is getting PS2 Gamecube/Wii or anything in that generation. (Haven't tested Dreamcast but I'll expect it to work). It doesn't complain about anything, the PS2 games I've tried just crash. I'm guessing the emulator in question is a placeholder for weaker Pi systems (Or the 4Gb ram isn't enough)

N64 games work... sorta. If you have it on the lowest resolution it runs relatively fast, if it's on a higher resolution for some reason it slows to a crawl.

Controller configurations when doing the N64 controller is confusing since it is asking for buttons for effectively a PS2/PS3/360 controller, so mapping it on the 64 is uncertain. I'll still be trying to figure this part out, not that i care for N64 games that much.

Anyways, guess that's an update on that.