Cool GTX
If the PC fails to BOOT
 
1) Instead of waiting days, pull the A/C plug, then push the power button to remove all energy from PSU, plug back in and Boot.
 
2) If it still will not Boot, clear the CMOS
 
 
X99 MB, important to keep CPU level while installing & not to squash it either.
 
Set the RAM Voltage manually ---- do not use auto, should increase stability @ boot

Sajin
Try running each gpu individually with the other completely removed from the system. Maybe one of your gpu's is causing the problem.

Sajin
Yeah. Sounds like the board is just defective. Have you tried booting the system outside of the case while sitting on some cardboard or wood?

Cool GTX

Arqrez

Cool GTX
 
Set the RAM Voltage manually ---- do not use auto, should increase stability @ boot

1) Thanks for this tip, I'll try it next time it refuses to boot.
2) I do try cmos but I can only do it using the clear cmos button, the manual or battery is out of reach due to gpus but it doesn't seem to help much.
 
How much voltage would you recommend me to set them ?

stock voltage the memory mfg lists
 
Note: also, do not squash the MB mounting screws - snug is not gorilla tight, you can damage the MB if over tightened
(I only use 1 finger & thumb to gently tighten the MB mounting screws)

Cool GTX
BIOS issues --- do the "BIOS dance"
1) Boot into BIOS
2) select default
3) save
4) reboot & enter BIOS (again)
5) edit BIOS
6) save BIOS (again) make the changes you need like memory voltage
7) Reboot PC
 
This is the "BIOS dance" --- just a phrase I coined, cause that is a lot of steps
 
 
 
Back Panel (page 1-10)
 
▶Clear CMOS Button
There is CMOS RAM present on board that is powered by an external battery to store
system configuration data. Using CMOS RAM, the system can automatically boot into
the operating system (OS) every time it is turned on. If you wish to clear the system
configuration, press the button to clear the data.
 
 
Make sure you confirm factory default jumpers & BIOS settings are selected, unless you chose a different setting
 
I would not mix RAM size 4GB / 8GB on the MB, use one or the other

Cool GTX
16 GB RAM is fine for most users, you will probably never use more than 8GB anyways

ragevirusqq
I used to have this board and I used Kingston hyper x predator. After returning the first board (because it had bent pins out of the box) I got one to post. This board however would never post and I would get that red led with any changes to the ram voltage and or timing. Even enabling XMP would make the board not boot. If the overclock Genie (which is total garbage on that board btw) was used it would also cause intermittent fails to post and that red led would turn on. To get it stable i had to turn of xmp and make sure everything was run at stock. I could then restart (but not pull the power) and make manual overclocks to the board. I could never get my 5930k totally stable above 4.3 with that board but on my X99 classy its totally stable at 4.5. 
 
MY opinion is that that board has some kind of issue in the traces or VRM causing power fluctuations or something similar. Always seemed like dirty power to the ram.
 
anything faster than 2133 on the ram would cause it to not post as well. 

Arqrez

Sajin
The 3000 ram will boot at 2133 speeds when first installed/booted. Only after enabling xmp mode will the ram run at 3000MHz.

Same, it is auto oc though, it starts at 2133Mhz and auto OC once booted

transdogmifier
According to this (https://forum-en.msi.com/index.php?topic=184137.0) forum, it's a power fail indicator?
 
I would, if you could, make sure all the power connectors (including the 8 PIN one for the CPU) are properly seated and
if that doesn't help, try a different PSU..?