I'd do something like that. You don't want to buy separate memory modules, and HOPE they work together. Even with identical part numbers, they often won't. They MIGHT, but they also MIGHT NOT. Buying them in a set is the only way to be sure they will play nice together and run in dual channel.
Everything else is compatible, but I'd seriously consider a better power supply. NOX isn't the worst out there, but the quality of their products is definitely not on par with the rest of the build, and if it was my money, I'd replace it with a higher quality unit to protect my investment.
At the forefront of many memory issues is a well known tenet of the builder and enthusiast community that while mixed memory (Memory modules that did not come together in one kit, regardless of whether or not they have the same part number or have similar specifications) certainly CAN work together in some cases, OFTEN it simply will not. Right up front I'll tell you that if you are trying to get sticks to work in the same machine together that were purchased separately, even if they are otherwise identical according to the kit or model number or if they would seem to have identical timings and voltage requirements, there is STILL always a very good chance that they simply will not work when used together.
(There is also a good chance that you MIGHT be able to get them to run together IF you are willing to not be impatient, listen to and understand what it is you need to do and follow the steps necessary to determining if they will "play nice" or not.)
A word of advice. If you just purchased this memory, and for whatever reason you bought two separate sticks of the same memory instead of buying them together in a matched set, see if you can return them for a refund or credit towards buying a similar or same set of matched sticks that come together in a kit.
It is ALWAYS better to have matched modules because from brand to brand, or even within the same brand, in fact, even when the part numbers are IDENTICAL, there can be anything from simply slightly different memory chips that were sourced from different bins at the end or beginning of a production run to entirely different configurations altogether even though the model numbers seem to be the same.
Case in point. See that these all use the same part number but have different rows, different ranks and all three use different memory chips, known as IC's, which make it highly likely that they also ALL have different primary, secondary, and tertiary memory timings which is going to weigh heavily towards them being incompatible.
Some manufacturers even reuse model numbers when they discontinue a product. Point being, the ONLY time there is no question whether or not the memory is all the same, is when all sticks came out of the same blister pack or packaging and were sold as a tested kit. Period.
In order to determine if differences in the memory, or a need for increased voltage when using more than one stick (Especially if you are running three or more sticks) are responsible for the problems you are having you will always want to begin your troubleshooting process by attempting to boot the machine with only a single stick of memory installed.
Also, for practically every consumer ATX four slot motherboard that's been sold since at least as far back as about 2014, the A2 memory slot which is the second slot over from the CPU socket, is THE slot that is most commonly designated for the installation of a single memory module. Slots A2 and B2 are almost always the slots specified in the motherboard memory population rules for use with two modules. If you need to install a third module I have no opinion on which of the remaining slots to use for that (Nor do I recommend using three modules unless you have a triple channel board OR you KNOW your motherboard supports Flex Mode channel operation), but typically since the A1 slot is right next to the CPU socket and often interferes with the CPU cooler or fan, I'd say the B1 slot was probably just as good.
Honestly, I don't ever recommend that you HAVE three modules installed anyhow UNLESS you have a motherboard that supports triple channel configurations or flex mode operation. Using memory in pairs is always a better option so that normal dual channel operation will occur.
And that's another thing. When it comes to memory there are no "single channel" or "dual channel" memory modules.
There are ONLY "memory modules" and the motherboard and CPU architecture will determine whether or not dual, triple or quad channel operation is possible based on the architecture and how many modules are in use.
Occasionally though there are situations where it might make sense to run three modules, like in cases where you have a six or eight slot motherboard that supports triple or quad channel operation, AND, some boards CAN use three modules in a FLEX type mode where two of the modules will operate in dual channel while the third oddball module will run in single channel.
Also, on some FLEX mode supported boards you could also have two modules running in dual channel while a third module runs only in single channel without benefit of the doubled bandwidth offered by dual channel operation.
I'd avoid oddball configurations like that though unless you know FOR CERTAIN that your board supports FLEX MODE operation, because many motherboards will simply run ALL modules in single channel mode when an odd number of modules are installed.
So if you think you will ever need 16GB, or 32GB of memory, then buy THAT amount of memory from the start so you can get it all in a matched set that has been tested, and eliminate a lot of problems right from the start. Otherwise you might be seriously upset later when you find you need to by the entire quantity again because you can't seem to find any memory later on that will work with what you already had.