I combined it with the AMD Ryzen 5 3400g. Be careful with the processor you choose as it should have an integrated graphics card. The 3400g boxed version comes with a very large heatsink/fan that cannot fit inside the Asrock. The heatsink/fan that comes with the Asrock packaging is not suitable for the 3400g. So calculate an additional possible cost for a heatsink/fan - depending on the processor you will use. After doing some research, I ended up with the Noctua NH-L9a-AM4, which I was satisfied with as it is completely silent (I would like to remind you that the Asrock is perforated, so be careful about what you put in terms of sound)

The best there is.
If you don't hold it in your hands, you can't understand how small it is! It's like a power supply and it can be even smaller! Incredibly easy to connect the processor to the motherboard (first time) and the cooler. * The wraith stealth cooler fits comfortably if you remove the amd logo cover.
** It comes with a suitable cooler in the box. It may just not be as efficient.
It supports nvme drives, which is the best for now (Gen3). It can have a total of 4 drives!!!

Five stars! The laptop broke and this was the best solution. It has a smaller size than a computer power supply and is compatible with all possible AMD APUs such as Ryzen 2200g, 2400g, 3200g, and 3400g.

The A300 version comes with a case, motherboard, cooler, external power supply, CD with drivers, two SATA cables, screws, and rubber pads. The A300W version also includes the m.2 wifi module. You need to add a processor, memory, hard drive, and operating system.

I set it up with a Ryzen 2400g, the stock AMD processor cooler (it fits as long as the fan mask is removed, the fan is turned 90 degrees, and the blades on each screw are removed), and the cooler paste. Note: The cooler for the 3400g is not compatible. Temperatures: 34°C to 42°C idle and up to 70°C under load in a vertical position, on a desk where it gets airflow.

I also added HyperX Impact HX426S15IB2K2/16 16GB (2X8GB) SO-DIMM DDR4 2666MHZ CL15 DUAL KIT memory. Note: It requires dual channel. And a Samsung 860 Evo 250gb SSD. (It accepts 2x 2.5" hard drives and 2x nvme hard drives).

The Vega 11 Graphics uses about 2GB of RAM and performs well with Photoshop and Autodesk Fusion 360 while running Chrome with multiple tabs.

A small love, a beastly jewel. I paired it with an AMD 3400g and it worked straight away as it was a new batch with an upgraded BIOS from the factory, as stated on the box (be careful, the cooler of the 3400 doesn't fit, so go for a Noctua low profile or, like I did, use the cooler of the 2600 and luckily it fit - of course, you can throw away the one it comes with). I also used HyperX 16GB 2933mhz RAM, the maximum recommended MHz, an M.2 NVMe hard drive (if I remember correctly, it doesn't support regular ones), an SSD 850 Evo, and a mechanical one. I also bought extra USB ports from eBay (couldn't find them in Greece) and the 3168 wifi/bt module (I consider the rear audio jack overpriced and a waste of money, since it's mostly for show and I will be using HDMI/bt audio for my TV > soundbar or simply the front jack for stereo speakers, otherwise an external sound card is a better option), but with all these components, you need to be careful and patient to fit the cables. Speaking of performance, always with the 3400g - which, for me, is the ultimate combination and the only way to go to finish it off, both technically and psychologically :P - although I don't do much gaming, it can handle games like Shadow of the Tomb Raider, Call of Juarez Gunslinger, Street Fighter 5, COD WWII with good FPS at 720p med-low settings, and of course, it can easily run all emulators like MAME, Saturn, PS, N64, Wii. It also handles video editing at 1080p h.265 with good rendering times, although I haven't tried it at 4K. Movies in 4K, Kodi, and Netflix are a given, but I struggle a bit with HDR on Win10 and a 4K TV, although it's not the machine's fault. I also always have 10+ tabs open in Chrome and a TV card for Digea. Dimensions are 16x16x8.5. I won't hide that I was considering the NUC and Gigabyte Brix, but the graphics we can have with the 3400 can't be found in any Intel and at a much cheaper price. The slight noise bothers me a bit (compared to the aforementioned silent small ones, maybe with a Noctua fan the noise would decrease), but it's worth it, its power and reliability can't be compared to any other mini PC, even at twice the price. With a used Ryzen APU, used 2x4GB 2666 RAM, and an SSD, you can build an awesome and beautiful HTPC for 250 euros, something we couldn't even dream of a few years ago.

Update 1: While waiting for the x300 (hopefully soon, although they didn't make a big upgrade unfortunately, but if it's at a good price, I'll probably get it out of curiosity), I removed the 3400g and tried the 3200g, lowered the voltage (temperature dropped) with 4+4 RAM at 2666 and increased it to 2933, and it works PERFECTLY, stable and fast (with BIOS version 3.60H). I should also note that the Intel 3168 and 9260 wifi cards work great, and from what I've read, the AX200 as well.

Regarding the fan, switching to Noctua might not be worth it in this case due to the cost. If you lower the fan speed on the stealth cooler from the BIOS, the noise decreases significantly and the temperatures don't have a dramatic difference compared to the L9i. Additionally, you can place a 120mm PWM fan on top of the heatsink to control the speed. I tried the be quiet! Pure Wings 2 and saw a 3-4 degree drop.

Update 2: After some scratching, I decided to modify it, unfortunately a bit hastily and without the most suitable tools, more like an experiment, but I still like it and I think the white color suits it well. The size comparison is based on the Thermaltake Core V1 Snow

I combined it with a Ryzen 3 2200G and it really is worth its money. A little more economical than building a tower for the same processor and with lower power consumption (16w with the screen off and the plex server just on standby without streaming). The stock fan is okay, but not good enough, I plan to replace it with a Noctua for better performance and less noise.

With Ryzen 5 3400G, anything else in such size is truly ashamed. Ideal for any use except for powerful gaming and rendering (although it is decent for simpler uses of them). It would be good to combine it with a low-profile cooler. However, be careful, the UEFI must first be upgraded with a previous generation APU if you want to use the 3X00G series.