Ensure RAM enters Safe Mode during XMP application
Consider setting the to VCC voltages near 1.1V and observing the outcome.
Just changed frq to 2666 and adjusted VCCIO to 1.16 and VCCSA to 1.1V, and it started working properly—great news.
Failed to post and entered safe mode booting with both 3200 and 2933 settings using VCCIO at 1.16V, VCCSA at 1.1V and RAM voltage at 1.36V.
You might need to keep using 2666 due to the memory controller, but you can attempt to adjust the timing manually.
I started at 2800 and kept it that way!
Intel doesn't receive much benefit from memory speed improvements, unlike AMD.
Use VCC at 1.14 volts and RAM at 1.37 volts