I going to attempt to answer this with my limited knowledge on storage. I’m not personally a content creator but let’s see what I can come up with.
Best case is all NVME storage, 4.0 for the fastest possible configuration. But that’s expensive right? So that’s out. Also only x570 has full 4.0 support.
For your first drive you’re definitely going to want an NVME SSD. Improved boot up times, faster program load times and the like. If you get 512GB, I’d say it’s just OS and programs. But a Drive 1(or your C Drive) at 1TB? You can keep your most current projects/what you’re working on at the quick and ready. Load up your project file and work off of the drive easily. No matter the size, you’re going to want your C drive to be an NVME SSD no doubt. I suppose 4.0 is a nice quality of life thing on Drive C. The way I see it you’ll be moving things most often to your C drive to work on. So the read/write speeds will be nice. But technically speaking, speed differences between 3.0 and 4.0 are only seen when moving LARGE files. And the way I see it, you files won’t be too large at the start. (Read Paragraph 8).
I see your Drive 2 (Drive D) as long form projects (ones that will take time/you only work on it sparingly/recently completed projects that you may reference). Meaning you’re going to access it but not as frequently as Drive C. A 2.5in SATA SSD will do you solid here. A bit cheaper than NVME SSDs, but still solid speeds and equal in terms of longevity. But if you have the budget? Another NVME SSD can also fill this slot. Personally I it should stop here. Get 2 TB if you’re so inclined. Where Drive 2 is both your recent projects and scratch drive. But let’s continue.
Source media would be your recorded clips right? You can choose where you store that I’d assume when you go to transfer from your phone to your PC.
I see Drive 3 as the ‘vault” so to speak. Old completed projects, old thumbnails, old RAW footage. Technically speaking this is your least used drive. An HDD will work here and technically allows for the cheapest mass storage. But you said no HDDs, so again. 2.5in SATA SSD will do.
I think the rule is 80%. After formatting a 1TB drive has 931GB of usable storage. Or 745GB using the 80% rule. At 80% capacity is when SSDs slow down, so you could technically store a few games along with projects on Drive C without seeing slow downs.
Although, IMO I think your overestimating how much storage you’ll need. You’re just starting right? So that would be like 1080p at 30/60FPS. A 10 minute video would be, what? 2 GB? Let’s say 10GB max after edits, effects, and visuals?
A 1TB C drive and 2TB D drive will last you quite awhile in my option. (Unless you’re recording in 4K? That changes things.)
If you really wanted to be set up for awhile. I’d get 2 NVME SDDs to install in your mobo.
Storage is expandable. You don’t need to account for everything right now. Install more down the line as you see fit.
But in the end, your budget, your PC, your property. Do what you think is best.
Any other Redditor with creation knowledge, feel free to call me out on BS. But anyhow, that’s my spiel. I may have missed something, so I’ll be editing but feel free to discuss/ask questions as you please.