Haven't built a PC in 10 years

Been using a Z97 chipset with an i5 and 1080TI as a work desktop. Figured it's time to upgrade and my budget doesn't have to be approved by the wife, so going all out.

9800X3D w/CM MasterLiquid Atmos 360 EDIT: Went with Noctua 15 thanks to comments. X870E Taichi GSkill Trident Neo 32GB NZXT C1500 Platinum PSU be quiet! 500FX ATX Tower Samsung 990Pro 4TB Keeping the 1080TI for now

So I literally found out in the last three days so many things changed, I feel like a complete noob, and wonder what else I should know. Like SLI is not a thing anymore. OK. There's now liquid metal? OK. Liquid cooling became much easier, so the AIO was a no brainer. What are the other surprises I should expect without having looked at PC building for 10 years? Thanks in advance.