What does RAM (O.C.) on motherboards mean?

[jaedenzt]

I'm planning to start my first build soon but I need some assistance. I see that on Gigabyte's website that the Z370 Aorus Gaming 5 has "support for XMP up to 4133MHz and beyond" and it supports RAM speeds up to 4133MHz, but anything after 2666MHz has the letters (O.C.) after it. Does this mean that if I put in any RAM over 2666MHz its speed will be set to 2666MHz at max, or is it that 2666MHz memory can be overclocked to 4133MHz, or is it just like to say that it overclocked the motherboard and it might get hot?

 

[Tolis_GR]

DDR4 ram has base clocks either 2133, 2400 or 2666 mhz. Anything higher than that is actually overclocking the ram. It depends on the ram you will buy how much it will be able to overclock. It will be written on your ram specs. Your motherboard supports up to 4133 mhz or beyond, which are the highest ram clocks to my knowledge. You simply configure your bios settings and select the desired ram frequency. No harm at all