I did ask if a bigger case would be better for airflow and they made a couple of suggestions.

Also asked if going completely fanless was the best option and here's what they said:
"You have to remember we have sold tens of thousands of system over the years, with at least 60 - 70% of them being fanless systems and quite a few going abroad to warmer countries so if there were any issues with the heat we would know. Don't get me wrong, any 65W CPU and reach 100C under full load but that's absolutely fine "

"...you didn't say what enclosure/fans/CPU cooler/etc you're using,"

In the end I just decided to stop faffing and make an order - supply issues determined the power supply, but if I need more or different, then that can be swapped out later.
It came together as:

- be quiet Pure Base 600 Silver ATX Gaming Case
- TUF B550-PLUS GAMING AM4 ATX Motherboard
- Ryzen 7 PRO 4750G 3.6GHz 8C/16T 65W AM4 APU with Radeon Graphics 8
- Vengeance LPX 16GB (2x8GB) DDR4 3200MHz Memory
- NH-P1 Passive CPU Cooler
- Nightjar 450W Fanless Modular SFX Power Supply, NJ450-SXL
- Samsung 970 EVO Plus 250GB M.2 NVMe SSD (3500/2300)
- 870 EVO 1TB SSD Solid State Drive
- 870 EVO 1TB SSD Solid State Drive

Apparently this is something new: Noctua NH-P1 Passive CPU Cooler

Thanks for suggesting Ubuntu - I've got versions of that and mint so plenty to play with.

That cpu cooler looks impressive and if it performs well then it helps keep the noise down. If you find that it does not quite do the job then the link says it can have an added 120mm fan to assist so you have the ability to improve cooling if passive is not quite adequate. That whole build looks good to me.

Apparently those coolers have just arrived - I saw that about back-up cooling and have asked them about adding the NF-A12x25 LS-PWM fan... at £26.50 the fan seems like a good idea as a 'just in case' thing.

newlinuxmint20user,

I share obobskivitch’s concerns about the A520M-A board.
I had problems with a similar ASUS PRIME A320M-K motherboard using a Ryzen 5 3400G CPU. For whatever reason the amdgpu driver simply refused to load, despite numerous attempts.

Using the same CPU on a MSI B450 board there was no problem whatsoever.

To play it safe I would be inclined to request a better quality board from MSI or other vendor.


Summary:
The ASUS PRIME A320M-K motherboard on the Xenta MT Ryzen 5 3400G desktop PC does not load the amdgpu driver from the Linux kernel, as it should do, on Linux Mint 20 and consequently causes screen tearing.
I was obliged to return this PC to Ebuyer UK.

Details:
I am a regular builder of Linux PCs, including the AMD Ryzen 5 3400G CPU and MSI B450 Tomahawk MAX motherboard combination.
Using this motherboard, the amdgpu driver loads correctly from the kernel, either 5.4 or 5.9, in Linux Mint 20, Ubuntu 20.04 and EndeavourOS in every instance.

Comparison of the inxi -Fxz outputs for ASUS PRIME A320M-K (Linux Mint 20) and MSI B450 Tomahawk MAX (EndeavourOS) clearly shows the difference with regard to the loading of the graphics drivers.

It is possible that a more recent Linux kernel has solved this problem but I would recommend further research or a better quality board.

In the end they put forward a different board and I went for that:
TUF B550-PLUS GAMING AM4 ATX Motherboard

I'll respectfully disagree with them that A) 100*C is inevitable for even a 65W chip and B) that 100*C is 'absolutely fine' - that's at (or beyond) critical temperature for most any desktop CPU ever made, and will result in significant clock throttling (if not an outright shutdown condition). There's doing fanless right, and just unhooking fans so you can say you're fanless.

Was not aware there were supply issues with the PSU - that makes sense. Again the Silverstone model isn't 'bad' it just seems like a weird choice for a full tower configuration (when you get the machine you'll see what I mean - it will likely be on an adapter plate to fit into the PSU mount.

On the rest, this looks like a sane build.

Yes this has gotten a lot of press, don't buy the hype that it 'invented' or 'is the first' passive cooler - this was all the rage a few years ago, it seems to come and go in cycles. This is Noctua's first attempt at it, and I expect it will work fine (just due to its size). When this was last popular, CPUs that had an honest 35-65W TDP (and realize most modern chips that number is completely made-up) could run passively on similar heatsinks, or passively as long as the case itself provided some minimal airflow (but a 140mm fan at 700 RPM or something of that sort will be essentially silent as well). I actually own one of those 'earlier' heatsinks, from Thermalright, and it keeps a 65W i7 (which sensors report never exceeds around 55W power draw) under 60* C with minimal airflow. With a typical fan mounted it can keep an FX-9590 (which is probably more like 165W (!!)) at around the same. From comparisons I remember reading years ago, the 'bigger' (and harder to acquire and more complicated to install) passive heatsink from NoFan would've shaved a few more degrees off, and I think the Noctua unit slots in between those two in terms of size, so hopefully it works out well enough with the Ryzen. Bear in mind, it will run 'fanless' more or less no matter what, the question is 'is it throttling down?' - so keep an eye on temperatures + clocks, just because it runs fanless at 2GHz at 99* C doesn't mean 'its good' - if that's the case you should add a fan and let it run at full speed again, even if it means a bit of noise (again, I'm thinking more like a 700-1200 RPM fan, not a 6500 RPM screamer).

I can't speak to the temperature business but have asked them to add a fan as suggested by computersavvy

The original box was going to be Antec VSK10 Micro ATX Case - which might have been the reason for that - in the end I asked for something bigger as I wanted an internal DVD drive and something bigger for air flow.

The recommended PSU Nofan P-500A Silent 500W Fanless 80+ GOLD PSU was not in stock, but looking again today I see there is another option: Seasonic PRIME PX500 500W 80PLUS Platinum Fanless Modular Power Supply

What do you think - if it is not too late maybe worth asking them to go for that instead?

Having Never used an linux or M2 drive before, does the hardware need a particular setup i.e. does it need partitioning in a certain way to be able to run mint and ubuntu?
e.g. a partition for each oS and separate partitions for user data (/home)?
But maybe this is a question for a diffenent sub forum section...

I don't see an 80+ spec from what you posted on the SFX, but if its not 80+ or worse than 80+ Platinum (which is basically the best) I'd probably swap for the PX500 if the price difference isn't huge.

On setting up the M2 - it will 'behave' like a normal hard drive to the machine, as in it will look like any other block device, it just won't have a /dev/sd* name, it will be nvme0 or nvme1 or what-have-you. I'd probably pass on trying dual-boot as the first thing you do - pick one distro and get that working and get more familiar with its configuration and then pursue dual boot later if you like. Your ideas on the partitioning is roughly what it would take however.

Extra £39.10 to swap to the other PSU

The hype on the PSU says:
450w seemed potentially limiting too - I ask them to swap it over - don't think they are in the workshop over the weekend so the build should not start until Monday/Tuesday.

Anyway, many thanks to you and the others for pointing stuff out - I will take your advice on a single OS to begin with too

450W or 500W will either-way be more power than this machine needs, even if you added a dGPU at some point, but having the higher efficiency unit is a nice add-on because it will reduce how much heat it has to deal with (which matters for fanless systems).

Linux Mint is an excellent distro. Just as an FYI I learned the hard way with very similar hardware that I needed to install the "Edge" edition of Cinnamon, some kind of special edition that handles the Renoir graphics on the Ryzen card. See my tale here: [URL="//https://forums.linuxmint.com/viewtopic.php?f=46&t=347254"] Once I did that, it worked great.