Hello,
I was given this motherboard as compensation from ASUS because they couldn't assist me with my X48 model. It took me !FoReVer! to hunt down the proper components (CPU & RAM) to be able to properly test its functionality. It's well beyond any Statute-of-Limitations, now.(*) I presume it was a refurbished model they'd sent me -- but in any case...
It has a boot-issue.
I've tried my darndest researching the matter, and can't deduce how to go about it. Is it just that they (ASUS) sent me a bad board?
When I boot,
It takes ~10-Sec's~ to boot. Then, it takes a couple seconds to initialize the GPU, meaning I don't get to see POST. However, once the image loads; it stays hung on the "ROG" Screen. After multiple-reboot efforts (sometimes just once), I can get into BIOS and load operating system.
*I have yet to stress test it, any ... but, it will randomly (very randomly) crash, at times.
These two factors are the only concern with the build.
For some bizarre reason, I have to boot+reboot+reboot to load/boot.

-components-
• 750W Corsair TX750W (PSU)
• 6GB EVGA GeForce RTX 2060 KO [06G-P4-2066-KR]
• 6× 2GB Corsair Dominator-GT DDR3 @ 1866MHz (RAM) [CMT6GX3M3A2000C8]
• 1× 512GB SanDisk Ultra SSD (C:/)
• 1× 3TB Seagate Barracuda HDD (D:/)
MoBo: ASUS X58 Rampage III Extreme (LGA-1366)
CPU: Intel Core i7-990X (+DeepCool Genome II [BK/GN] 360mm)

I virtually have done nothing except assemble and install the O.S. (W10-x64) -- and configure the RAM to 1866MHz...
I'd hoped flashing the BIOS doesn't become necessary ...
BIOS Vers. - 1401
...
As far as why it (not-frequent) randomly crashes... I don't know ... but as for the boot concern; I can't figure out for the life of me how to go about it. It's very inconveniencingly-frustrating having to multiple-reboot attempts to load to O.S.
...
Bad RAM maybe?

-

It's been sometime since the case was initially disputed; probably since back in ~2015~ from when they'd swapped it to the X58. I've only been (finally) utilizing the 6-Core CPU (+III-MoBo) for a short duration ... as it has had performance issue(*),, I'd didn't want to potentially damage anything. >.< (but now could care less--I just want it to function properly)*

*EDIT*
*Also,
It took a minute, but I "Bench-Tested" it with solely 1×RAM Module [+GPU /etc. (Exclusive-Necessities Only)] at a time... across all 6×Modules.
6 for 6 had the boot-hiccup.

I was going to suggest dropping the memory to three sticks, total of six GB for a test. Place in appropriate slots.

Pastulio
I virtually have done nothing except assemble and install the O.S. (W10-x64) -- and configure the RAM to 1866MHz...
I'd hoped flashing the BIOS doesn't become necessary ...
BIOS Vers. - *PENDING*
...
As far as why it (not-frequent) randomly crashes... I don't know ... but as for the boot concern; I can't figure out for the life of me how to go about it. It's very inconveniencingly-frustrating having to multiple-reboot attempts to load to O.S.
...
Bad RAM maybe?

-

It's been sometime since the case was initially disputed; probably since back in ~2015~ from when they'd swapped it to the X58. I've only been (finally) utilizing the 6-Core CPU (+III-MoBo) for a short duration ... as it has had performance issue(*),, I'd didn't want to potentially damage anything. >.< (but now could care less--I just want it to function properly)*

*EDIT*
*Also,
It took a minute, but I "Bench-Tested" it with solely 1×RAM Module [+GPU /etc. (Exclusive-Necessities Only)] at a time... across all 6×Modules.
6 for 6 had the boot-hiccup.

I was suggesting a bios update because it’s the first thing I would do if I suspected a motherboard issue. It’s a pretty easy and painless thing to rule out, or potentially fix, the issue.