Upgrading workstation CPU / Mobo to work with 4K (and maybe barely 6K)

Budget: $1500-2000

Purpose: This is a bit weird, but I want to edit 6K via proxies which means I need to edit 6K but only at 10 or 5 frames per second. So basically this should be a 4K editing workstation with maybe a little more punch.

The system I have now:

• i7 5930K
• Asus Rampage V Extreme motherboard
• RTX 2070 8GB
• 64GB G-Skill "Ripjaws 4" 8x8GB DDR4 3000MHz running at 2133MHz(I think)
• Cooler master MR 1000W power supply
• a 256GB samsung M.2 drive of some sort
• A mixed bag of drives.

So my major concern, and the purpose of this post, is to replace the CPU and motherboard. Everything else will stay the same, and I will address storage at another time. The only issue is that the motherboard needs to be ready to take storage. For example, it would be nice to have 2 m.2 slots, not 1.

I am thinking about going for the

Ryzen 9 3900X

• Will this CPU work with my existing memory? ( Remember the bad old days of Ryzen's memory issues.)
• Is this sufficient to edit 4K footage smoothly?

Asus ROG Strix X570-F Gaming ATX

• Has 2 m.2 slots.

PC gurus, in your estimation, can this rig play 6K footage at a whopping 5 frames per second?

Edit: Sorry, 6K raw, specifically braw (Black Magic Raw from the Black Magic Pocket Cinema Camera 6K)