krysta24

AF? Yes, AFAIK the best "bang for buck". Original one? No, unless you get one hell of a deal (like 50USD) or AF not being viable in your region.

While the GPU would be compatible with your MB you should be more worried about PSU. It might not be sufficient, quality has imporoved significatly (compared to what was used 10-15years ago) and on top of that PSU age. So If you want to upgrade GPU, you should imo also upgrade PSU at the same time. I get you have limited budget, but I wouldn´t risk and go the safe way.

I´m OK with 16GB, but it really depends on what you do. I don´t do big projects. (I´m still student) 8GB would be limiting for me too though.

Also all of MAX have out of the box Ryzen 3000 support

Is there any impact of new BIOS on older ZEN CPUs? I got one, but updating BIOS resets my (finely tuned ?) setting so if theres no motivation to update I won´t. It takes quite some time and theres (small) chance that it will be broken, so I would have to find new stable settings.

Run memtest to be sure memory isn't issue anymore

They're completely different, but SN500 has great price/performance ratio. SN750 it's better but IMHO overkill unless you need super fast SSD and in that case it would've been completely different (and there might be better options).

If your budget isn't tight go for 3333 CL16 and try to tighten timings. SN750 is good but if it's just gaming/office you can save with SN500.

Not much but at the same price higher is better. What's the difference in price?

I´m not saying that every RAM can do it, but mine certainly can. DRAM calculator for Ryzen is your friend. Overclocking IF might be good idea even with RAM running about 3000Mhz (but you have to test it out).

I don't have experience with Zen 2, but 2666 CL13 doesn't seem like a good idea unless RAM prices where you live are somehow totally crazy. Personally I'd grab cheap 3000/3200 kit. Use XMP and try to tighten up timings. That's actually what I did with my Zen 1. I used Adata D10 - 3000 CL16 (bought because of value in my region - not because it would be exceptionally good or anything like that). Tightened to CL14 and called it a day. Don't forget to run memtest after messing with RAM it can save you a lot of time later

You can try to run memtest (to rule out memory), but from your description I'm almost sure that all your issues are PSU related. They probably checked, but I doubt that they did anything beyond "it works", PC HW fails old one more so and PSUs are one of the components likely to fail. 1,5 years isn't that short period either.

Core of the issue is probably very old hardware, that I certainly wouldn't recommend to use in 2019 for any purposes. I'd recommend you replacing your system. The issue might be slowly failing PSU (or less likely MB). That might have problem providing providing power in that scenario. Do you have other issues than that? If yes than you might run memtest.

16 is OK definitely not "unusable". With that said amount of RAM you need depends on what you do in Davinci. I've heard it's quite demanding (I'm using hitfilm, so I don't have much experience with it). Concidering you'll have other 2 spare slots. Unless you know you need 32 for editing. I'd go with 16 in your situation.

Now we can move from there. Do you have latest BIOS? Is your RAM included in support list (you're using uncommon brand, going for something more mainstream would be preferable)? If so, does it pass memtest? Are temperatures OK (meaning have you seated cooler properly)? Can you try different PSU? (Preferably quality one) CPU is unlikely to be the cause of your problems.