Boot problems in mah pc

[Ricewind]

Howdy! I started having trouble getting my pc to boot a few months ago. While the pc is booting, it would from time to time freeze right after the time to press F2 to go to BIOS-settings had run out. I see an ASUS-logo, but underneath the logo there is no spinning balls going around in a circle to notify me that Windows 10 is loading. And it would happen from time to time, but not always. Everything is fine and dandy after I get to Windows desktop.

 

So far I've changed the CMOS-battery and made a clean install of Windows i.e. formatted the OS-drive and reinstalled. Before a reinstall of Windows, I tried to no avail to use a recovery drive to find, if something's wrong with the OS. The ASUS X-99 A -motherboard, the Intel 5820k, the two 8 gig DDR4 memory sticks and a Seasonic fanless 80+ Platinum PSU are almost nine years old by now. The OS-drive is a Kingston 480 gig TLC-drive that's about four years old and a RTX 2080 Super is maybe three years old. I haven't overclocked my CPU and the XMP-profiles for the memory aren't turned on at the moment, because using them caused stability issues. 

 

All tips and tricks to alleviate this are greatly appreciated! I don't intend to make any significant investments to my pc at the moment, unless it's an issue with my OS-drive or my DDR4 memory sticks that need replacing.

[OddOod]

I'd suspect either dying RAM or a mobo, though a dying SSD is also a strong possibility. 
Can you check the SMART data on the SSD and run a memtest?

[Ricewind]

Now that I think of it, I think I already checked the SMART status and memtest at some point. That leaves me possibly with a dying motherboard I was supposed to continue using my pc, until Windows 10 reaches end of life, after which it would’ve been a good time to do a thorough upgrade. Oh well, we’ll see for how long I can hang onto it. 
 

Anyways, thanks for the advice!