intel 14900K with Asus ROG strix Z790-E installation blank screen

[Etorix]

SuperMicro X11SPA-T Motherboard ($771)

This is actually a workstation motherboard. Suitable, but overfeatured and accordingly overpriced.
The most basic X11SPL-F would do, for almost half the price. Or anything from Supermicro whose name begins with "X11SP" (but not "A" after). (Dual-socket "X11DP" would be overkill.) AsRock Rack models would be EPC621D8U (or EPC621D6U). Gigabyte: MU71 (or C621-SU8). Whatever comes cheaper.

Software:
-Linux FreeBSD

This is either FreeBSD (CORE) or Linux (SCALE). MacOS (actually a BSD family member down under) or Windows (definitely NOT Linux!). Water or oil.

-RaidZ2

Provided in software by ZFS in any case. Disable any RAID feature in hardware.

Hardware:
-SuperMicro X11SPA-T Motherboard
-Intel Xeon Gold 6138 Processor 27.5M Cache, 2.00 GHz, 20 Core (is this processor compatible with the motherboard?)

Yes. Any LGA3647 Xeon Scalable x1xx or x2xx (1st/2nd generation). 1st generation are very cheap second hand by now—like "under $100".
For a home server (with up to 64 drives!?), I suppose that higher clock and fewer cores will serve you better (not so many clients, SMB uses only one thread per client).
These use Registered DIMM (RDIMM), or LRDIMM, not the Unbuffered DIMM (UDIMM) you're familiar with from desktops. Good news: Second-hand DDR4 RDIMM are also very cheap.

-Crucial T500 500GB Gen4 NVMe M.2

Whatever small and cheap drive you can find for boot.

-LSI 9305 24i

Make sure there's airflow going its way.
Beyond that, rather than buying more HBAs, you can add one or two of the expanders discussed here. Link the expander to the HBA, and then attach drives to the expander.

Heed the advice from @ChrisRJ : You have some reading to do before taking the plunge. About ZFS and drive layout (cannot change raidz2 vdev after creation!). And about SAS.

 

[Davvo]

IMHO you can use TN SCALE with relative ease for Plex streaming: you get a stabile system that needs low mantainance once properly set and reliable storage.
You can spend little money for it (ie 400 USD for PSU, MB, CPU and RAM).
You will have to learn a bit, but if you are a bit tech savvy you won't have problems.

 

[Etorix]

Good point about the PSU, and PSU sizing for the drives!

Proper Power Supply Sizing Guidance

I've seen about 1,000 threads like this one where people decide that they can power a dozen hard drives off a 360 watt supply. DO NOT DO THIS. I've seen another 1,000 threads where people decide to buy the cheapest power supply that they can...

www.truenas.com