Lowering speed of a RAM, does it lower its timing ?

The Strange · September 19, 2018

Hi guys, I just bought my 1st gaming PC since few days, but only for now just have to get the RAM to be completed build.

CPU = core i5 8400 with motherboard B360 AORUS Gaming 3

Well, I was going to get this model:
Team T-Force Delta RGB 16GB(2x8GB) DDR4 2666 CL15

But unfortunately it was out of stock currently in my country and it looks like its gonna take much longer time to be available again more than i thought so i started to look for another available one.

Well, anyways a different model just showed up with 3000 Mhz speed and CL16:
Team T-Force Dark 16GB(2x8GB) DDR4 3000 CL16

It's a little cheaper and higher speed, but of course I will be restricted to 2666Mhz cuz it's the max motherboard speed of RAM.

But someone told me before that when i use the RAM at 2666Mhz, which down from 3000Mhz, the timing will become at CL15 too, meaning that it will operate at 2666Mhz and CL15 like the 1st one here's starts my questions:

(1) I'm really confused, Is this information right ?? so both RAMs will operate at the same performance and so the only difference here is the RGB for the 1st vs NO RGB for the 2nd one ??

(2) There is also testing voltage for both of them: 1st RAM tested under 1.2 voltage and 2nd RAM tested under 1.35, will be there any compatibility issues because of voltage or the higher speed of the 2nd RAM (3000) ?

Sorry for long topic, i hope for some help.

Thanks in advance.