Sabertooth x99 won't boot XMP 2666

[pocketdrummer]

I have an Asus Sabertooth X99 with G.SKILL Ripjaws 4 Series 32GB (4 x 8GB) DDR4 2666 F4-2666C15Q-32GRR.

I have been using it for a week at the stock setup because I've been testing the processor. However, today I set XMP and adjusted the CPU speeds back to their proper setting and it would not boot. I then tried resetting the motherboard to factory defaults, reboot, chose XMP again, and when it reboot I got a single long beep and 2 short beeps.

As it stands I am not able to boot if XMP is selected.

I have been able to set it manually, but I'm worried the timings are going to be all screwed up. If I reset the motherboard to default, would the primary, secondary, and tertiary settings be the same? If so, I suppose I could just write them all down and set it manually.

[GSKILL TECH]

Test them individually to see if it is a problem with a module or something else..

[pocketdrummer]

Test them individually to see if it is a problem with a module or something else..

Is there a way to disable certain modules individually from the bios? I have a Noctua NH-D15, so swapping modules means reinstalling the cooler 4 times.

[pocketdrummer]

I've been testing a bunch of different settings and here's what I've found out.

I re-seated the GPU, and I believe that may have solved issues with the 1 long 3 short beeps.

I've also tried several different settings:
All back to defaults
RAM Multi at 2666
15-15-15-35 2T
DRAM voltage at 1.2v
Strap tested at 100 and 125

Tested and worked fine.

Reset back to defaults and changed the following:
CPU multi at 43
CPU volts at 1.21v adaptive
CPU strap at 100

Tested and worked fine

Added the RAM settings that tested fine to the CPU changes that tested fine:
Locked up within 3 minutes of testing Intel Extreme Tuning Memory stress test.

I then went through and tried CPU multipliers of 36, 38, and 40. It seemed fine with 36 and 38, but locked up again at 40.

Now I'm testing the multiplier at 43 and the RAM multiplier at 2400 15-15-15-35 2T. So far so good.

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So, I can run 2666 at stock CPU speeds. I can run the CPU at 4.3Ghz with the 2400 RAM multi. I cannot run 2666 RAM with 4.3Ghz. So, what's the deal here?

[GSKILL TECH]

That is the maximum for Adaptive setting.