I notice when i choosing memory on website www.newegg.com , there is option on memory like DDR4 2133 (PC4 17060), DDR4 3466 (PC4 27700), DDR4 3466 (PC4 27730). What is PC4? My friend tell me that when i choosing memory, u must use the same PC4 with the mobo in order to use memory. I gonna buy dekstop pc, so i don't have mobo yet, and i search on my selected mobo (MSI Gaming B150M BAZOOKA) , it doesn't have explaination about PC4. Can someone help me? Or it doesn't matter really at all about PC4?