Memory at over 2666 MHz Changes the Base Clock on X99 Motherboards?

[AlphaBravo]

"The MSI X99S SLI Plus natively supports 2133MHz RAM sticks, and I noticed that the 2800MHz Corsair Vengeance LPX sticks I was using were being bumped down to 2133MHz automatically. Using the Intel Extreme Tuning Utility that came bundled with the motherboard, however, I was able to easily boost this back up to its full speed, and even overclock it to a ‘safe’ 3733MHz due to the Vengeance LPX’s native support for Intel’s XMP 2.0.

One thing that should be noted about all X99 motherboards is that, when running memory at speeds higher than 2666MHz, the system will automatically change the base clock to 125MHz from 100MHz. This is a limitation of Intel’s CPUs and not a reflection on the motherboard.?

 

Source

 

I am considering purchasing the MSI X99 SLI Plus motherboard, but I am confused at to the statement quoted above. 

 

1.  Do all X99 motherboards really change the base clock from 100MHz to 125 MHz when memory is run at speeds over 2666MHz?

 

2.  Are there any drawbacks to having the motherboard change the base clock to 125 MHz?

 

[KemoKa]

Someone really please correct me if I'm wrong, but as far as I'm aware, X99 was introduced at a stage when DDR4 on desktop platforms was all but unheard of. Being the first commercial platform to support the new standard, its support for the full DDR4 specification is lacking. Just as preliminary DDR3 standards only supported DDR3 800 and 1066 without overclocks, DRAM speeds virtually unheard of now, DDR4 has the same characteristics with relation to X99. That's why it needs an overclock to support faster memory.

 

I'm really just saying what I've heard from observations of older platforms (My parents iMac only supports 1066MHz DDR3, so...) someone tell me if I'm just talking out of my ass.