I ended up getting the ASRock Z790 Taichi Lite last month for my i9 build because I wanted overkill VRMs without paying the premium. It runs incredibly cool. A couple quick tips from my setup:

• Go with a board that has at least a 20-phase VRM layout to spread the heat.
• Make sure your case has decent top exhaust airflow, otherwise even the best heatsinks will heat soak.

^ This. Also, unfortunately, I have to be the bearer of bad news about some of the mid-range stuff people hype up. I've had issues with boards like the ASUS TUF Gaming Z790-Plus WiFi where the VRMs looked great on paper but were just not as good as expected in a real stress test. I pushed an i9 on one last year and watched the VRM sensors creep into the high 90s within ten minutes... ngl it was pretty sketch. If you're buying this weekend, keep an eye on the ASUS ROG Strix Z790-E Gaming WiFi II. It's usually right at that 400 dollar ceiling. The power delivery is massive compared to the cheaper TUF or Prime lines—basically 18+1 stages at 110A. I swapped to that after my TUF debacle and the temps dropped by nearly 20 degrees under the same load. It's actually built for the current draw an i9 pulls when you unlock the power limits. Definitely go watch some Buildzoid videos on the Actually Hardcore Overclocking channel before you pull the trigger. He does these insane hour-long rambles where he breaks down the actual PCB quality and component choices. Also check the VRM spreadsheets on the overclock.net forums. Most people just look at the RGB but the actual phase doublers and MOSFET quality are what save your hardware from dying early deaths lol. Just make sure your case has actual airflow over the top of the board too.

Honestly, if youre looking to push an i9 without hitting thermal limits on the power delivery, you need something with massive heatsinks and high-quality power stages. In my experience, the MSI MPG Z790 Carbon WiFi II ATX is the absolute sweet spot for that 400 dollar budget. I've tried many boards over the years and MSI's VRM thermal pads and heatpipe designs usually stay way cooler than the competition in this price bracket. Youre looking at a 19+1+1 power phase setup with 105A smart power stages, which basically means the workload is spread out so no single component gets too hot while feeding that hungry i9. Ive pushed my chips on the Gigabyte Z790 AORUS MASTER X E-ATX too, and that board is a literal tank. It uses actual fins instead of just solid blocks of aluminum, which increases surface area for the air to actually move heat away. Tbh, as long as you have some airflow in your case, either of these wont even break a sweat. Ive seen people worry about melting things but modern boards have so many sensors and safety cuts that youll be fine... just focus on getting a board with a high amperage rating on those stages. Both these options are top tier for what you want to do. If you get stuck on the bios settings once you get it this weekend, just hit me up and I can walk you through some safe offsets to start with.