The CPU speed isn't keeping up with the memory capacity!
The CPU speed isn't keeping up with the memory capacity!
You're checking the specs for your setup. The i5-9400F supports up to 2666 MHz RAM, so it should work fine with your 8+8 GB 3200 MHz modules. The rumor about higher speeds isn't accurate—your CPU won't limit performance beyond what the RAM can handle. Just make sure the RAM is compatible and properly seated.
It all hinges on your motherboard. Review the details on the manufacturer's site.
Verify XMP support, search for an XMP switch at the top of the EZ menu (EZ mode). If unsuccessful, enter advanned mode (F7) and adjust timing, voltage at frequency manually.