Hello wonderful people! It's my first time reaching out for opinions and assistance on this particular subject... My system is brand new and running: Asus ROG Strix Z390-F Gaming (1401 BIOS Latest) Intel’s Core i9-9900KS Special Edition Corsair Vengeance LPX 32GB 2x16 DDR4 4000MHZ C19 XMP 2.0 (CMK32GX4M2F4000C19) When enabling the XMP II profile and reboot, the system fails to post over and over and reverts back to the default 2133MHZ memory speed after five attempts. When I enable the XMP II profile however manually change the memory speed to 3466MHZ (but no higher) and reboot, the system instantly posts and seems stable. (CINEBENCH/PRIME95) So my question really is, why could this be happening? I haven't changed the memory settings in any way other than enabling XMP II and reducing the operating frequency to 3466MHZ. I truly appreciate your time and support viewing this post. Thanks again, Jake Billing - YouTuber.