Question CPU/MOBO Support for RAM Speeds


Sep 16, 2011
Evening Folks,

i7-9700K supports DDR4 @ (up to?) 2666 MHz
Z390 AORUS MASTER board supports everything from 2133 MHz to 2666 MHz, or up to 4400 MHz (O.C.)

1. Would buying any RAM faster than 2666 MHz be a moot point due to CPU support?
EDIT: So I've learned the motherboard overclocks the memory once I enable XMP. But there seems to be a lot of debate out there on whether or not that works with Intel's CPU limits, as it will just default back to a lower speed.

2. Does installing RAM faster than 2666 MHz require more than plug-and-play?
EDIT: Like above, it seems I at least need to manually enable XMP - I'm still researching what further actions are needed such as manually setting speed/timing/voltages, or if that's all automatic.

Reading TomsHardware articles, I noticed a conflict:

From: "PC Memory 101: Understanding Frequency and Timings"
"The easiest way to exceed DDR4-2666 on any of this hardware is to use a Z-series (Z390, Z370, Z270) chipset with a K-series Core i5 or higher processor."

From: "How to Choose the Right Memory: A 2020 Guide To DRAM"
"So if, for instance, your system only supports 2,666MHz, there’s no point in buying RAM that’s rated for 3,600. You won’t be able to achieve the higher speed, and may wind up stuck at an even lower fallback speed."

Over the next four months, I'll be researching, ordering, and building a desktop PC. Self-imposed budget is $2K (VERY flexible, but I want to be practical). Primary uses will be Sketchup, an upcoming MMO game called "New World", and typical MS Office work. I've built 4 or 5 desktops in the last 20 years, but have ZERO experience overclocking anything. Hoping to really get into your guys' world.

Thanks for any help!
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