Upgraded a year ago up to 128gb and here's what I pulled out working great!  Has been sitting in a box safe-and-sound.

XPG GAMMIX D30 DDR4 Memory Module Whether you’re a gamer, PC enthusiast, or overclocker, you’ll appreciate the combination of the GAMMIX D30’s edgy wing-shaped design and excellent speeds of up to 4133MHz.

What’s more, it features Intel® XMP 2.0 profiles for hassle-free overclocking when you need an extra boost.

Features Specifications
● Unique heatsink design with edgy wing-shaped
● Supports Intel X299 platform and implements 2666MHz
● Fast speeds up to 4133MHz
● Intel XMP 2.0 - more accessible overclocking
● RoHS compliant ● Speed: DDR4 2666MHz ~ 4133MHz
● Module size: 8GB ~ 32GB *8GB: 8GB (8GBx1), 16GB (8GBx2) *16GB: 16GB (16GBx1), 32GB (16GBx2)
● Compatibility: DDR4 2666 CL 19-19-19 at 1.2V
● Operating temperature: 0°C to 85°C
● Storage temperature: -55°C to 100°C
● Operating voltage: 1.2V ~ 1.5V
● Dimensions (L x W x H): 133.3 x 44.7 x 8.1mm