Google “G-Skill RAM Configurator” and check for F4-4000C18Q-32GTZSW (not compatible).
The ASUS QVL for the IX Extreme list G-Skill F4-360017CQ-16GVK as compatible, where as G-Skill QVL list does not list the IX Extreme compatible with F4-360017CQ-16GVK.
So, on a cold boot first number Q-Code 15 (count: one thousand, two one thousand, three one thousand), Q-Code CC or Q-Code 49, always follows.
And on a cold boot first number Q-Code 25 and stops on Q-Code 32 (count: one thousand, two one thousand, three one thousand), Q-Code 55 follows. Or if it stops on Q-code 32 for a count of one thousand, two one thousand the computer boots fine.
No problems with G-Skill F4-360017CQ-16GVK on VIII Gene or VIII Extreme Assembly. Works fine on VIII Formula if using BIOS 2202 or lower. Hit or miss for any BIOS above 2202.