Question What is the absolute best ram I can use for a i9-9900k and ROG MAXIMUS XI HERO mobo?

[IdesOfMarch]

No budget, don't care about RBG. Just want the fastest most reliable ram available for this cpu mobo combo

 

[Aeacus]

According to your MoBo memory QVL list,
link: https://dlcdnets.asus.com/pub/ASUS/...OG_MAXIMUS_XI_HERO_SERIES_Memory_QVL_0320.pdf
fastest RAM Asus has successfully tested is the G.Skill Trident Z 4400 Mhz RAM in a 4x 8GB set (32GB). Namely these three sets:
F4-4400C18Q-32GTZR - Trident Z RGB
F4-4400C18Q-32GTRG - Trident Z Royal Gold
F4-4400C18Q-32GTRS - Trident Z Royal Silver