New RAM causing Post-BIOS boot stall

[JayBreaksGames]

Howdy!

 

First post here, not sure what the standard protocol around posts is, but I'll try to include as much (helpful) info as I can.

 

Issue & Context:

 

Recently a friend of mine sent me 2 sticks of XPG Corsair 16gb DDR4 2667MHz RAM that I want to include in my system. I currently have 4 sticks of Corsair 8gb 2133MHz in my system. 

 

I currently have an ASUS X99-Pro MoBo with a Xeon E5-2680 v3 CPU. 

 

After putting the new RAM in slots A2 & A4 (The side labeled DDR4-8 DIMM) the computer will sometimes stall at BIOS for several reboots, and then begin working again with no clear reason why.

 

In BIOS, it recognizes all 6 sticks of RAM, but for the A2 & A4 slots, reads "A-DATA 0GB 2667MHz." I take this to mean that it recognizes the sticks, but for some reason can't actually interface with the RAM.

 

The issue also persists if the new sticks of RAM are removed & the system is booted in original configuration.

 

Troubleshooting Steps Already Taken:

(Items entered in order attempted)

1. Turned the PC off and back on.
2. Turned PC off, turned Power Supply off, power cycled system, turned PC back on.
3. CMOS battery removed & computer restarted
4. New RAM removed & computer/power supply restarted

 

Please let me know if there's any other info or context that would help diagnose the issue! Thank you all!