The RAM you list is on the official AMD Ryzen compatibility list, so I would think it should work without an issue.

To see if RAM is compatible with your motherlist, check the QVL (Qualified Vendor List) of the motherboard. The Ryzen 2400G is a Raven Ridge cpu, so you should check here if your memory is listed:

https://www.asrock.com/MB/AMD/Fatal1ty%20AB350%20Gaming-ITXac/index.asp#MemoryRR

As you can see, it is not.

Another recommendation is to buy a set of RAM sticks if you want to run in dual channel mode. To efficiently run in dual channel mode, both RAM sticks should be identical and if you buy a set (2x8GB for instance) you're sure both sticks come from the same batch.

If you want to use the integrated graphics, get 2x8GB (or 2x4GB if tight on money knowing you will have to pull them out if you want more RAM later) RAM running at 2933MHz minimum. Even if you do not want to use the iGPU, Ryzen loves fast RAM like Phasmid said.

That first paragraph. That's something I had no idea of. Thank you for that information.

Yes, I do plan to upgrade from 16 gb to 32gb and the RAM speed on this stick is 2666 mhz, however, the BIOS sees it as 2133 mhz. I will put in the SSD tonight and see what I get with the single stick. Would dual channel mode and the RAM's 32gb total storage with 2 sticks total, remedy this or should I really return for faster RAM with potentially less space totaling 16gb with 2 8gb sticks?

Also, during the aforementioned scouring, I found this which states that the QVL no longer applies and it does seem that my system boots to the BIOS but again at 2133mhz instead of the 2666mhz but maybe either way I should get something faster.

So are GPU prices still ridiculous?

You will need to go into the UEFI and set your RAM at the correct speed. 2666 is the lowest you should go with that processor. If you feel that you need 32GB that is fine and you will then of course need 2x16GB modules as your motherboard only has two slots. Having one or two sticks installed should make no difference as to at which clock speed it works. It is when you add a third (not possible in this case) that you might have to lower the clock speed but it should never go as low as 2133, which is some compatibility speed to ensure your computer boots. Yes :-( but prices stabilised here and supply is getting better.

I remember that on Intel platforms you need to select in BIOS the XMP profiles for the RAM to work at maximum speeds. I don't know if on AMD platforms has a similar name. Be sure to check your manual first and if some BIOS updates are available.

As the others already said, better get 2 sticks for Dual-Channel, and if the price increase is not too big, go for 2933Mhz at least. Below are some very good videos related to RAM.

1 vs 2 Sticks RAM

RYZEN TEST: Does RAM Speed Matter?

Does Ryzen Really Need Fast Memory? Guide for Gamers

AMD Raven Ridge 8GB vs. 16GB Reserved Memory

I'd have to point out that for most people 32GB is overkill. Witcher 3 for example runs fine on 8GB of RAM, as do almost all games. If you use your computer for more 'work' type tasks- manipulating large pictures, video editing, databases etc- 32GB makes sense, if it's for gaming primarily and light productivity or internet browsing, even with Chrome, 16GB is fine, for a couple of tabs. RAM is one of those things where you only need enough of it, adding more above that has very quickly diminishing performance returns.

Also I'd advise checking the XMP (preset RAM configuration data) setting is 'on' in BIOS/ UEFI first rather than manually making settings on the RAM. I have a GB board so can't comment on how to check it or if it's automatically applied on ASRock.

edit: checking for new BIOS is a good idea, but in this specific case the 2400G is a new release, it only works in a MB with a very recently updated BIOS anyway. To clarify, the APU Ryzens only get significant performance boosts with fast RAM if the iGPU is going to be used, as their configuration is uniquely different to other Ryzens. The theoretically equivalent* non APU to a 2400G (4 core/ 8 thread 1300x) uses 2ccx core clusters as a 2 cores/ 2 cores config with each pair of cores communicating across the cluster using the Infinity Fabric whose speed is governed by the memory clock, hence the big performance boost with fast RAM. The 2400G though has 2ccx as 4 CPU cores and 11 Vega cores so Infinity Fabric is only used if the Vega cores are used and the iGPU is on, if it isn't the performance boost from fast RAM is similar to for an Intel chip and not very significant though may be worth it depending on use

*Practically a 2400G is closer to half a Ryzen 1700 (which has 2 ccx as 4cores/ 4cores) than to the 2c/2c 1300x.

I guess it could be overkill but would it help in situations where one might leave like 10 tabs open in say, chrome (specifically SRWare Iron), including youtube, while running a game like Witcher 3? I always have to wonder whether more RAM would've handled the load better but 16gb is enough to play games and have tabs open in the background, then I will definitely go back to a dual channel setup with a total of 16gb because gaming and opening an ungodly number of tabs at the same time, is what this build is all about.

Note: The only reason I got this APU was because it was on a deep discount - 133 USD versus the any of the Ryzen 5's and it seems like it would suffice for my needs as previously, I had an Intel i5 4690k, which this should be able to easily outperform considering its specifications. I also thought having an APU would be great for troubleshooting any issues and it would also come in handy in any "in case of emergency" situations. So, that's the reasoning behind why I got this despite intending to primarily use my 1080 gtx for this build.

<mumbles something about rich people replacing something as good as a 4690K>

Lots of tabs open in a browser...Does Chrome eat memory like there is no end to it? Using up more than 8GB (if 16GB total but OS+game takes 8GB) for the browser is an awful lot of tabs open.
Aye, not as important as in the eight core models, with whatever number of cores disabled. If I say something dumb, it is good that someone else corrects me.

Either that or CPU. I'm unsure but I'm guessing that having tabs open in the background and forgetting to close them while gaming would put a load on something but that's why I'm asking here to see whether someone knows.

The 4690k is inflated in price right now and is definitely beyond the "bang for your buck" even in case you have the hardware to run it. A couple weeks ago, I saw it at $449 and I was thinking, wow, it still got it but there are way better options out there for that much. Especially, in the AMD camp.

No they are actually going down.

True, I have 16 and rarely use over 8.
I swapped the sticks to let the other one work a bit too XD
Probably lots of RAM is useful expecially for VMs.