Overclocking with XMP is the best configuration from the RAM manufacturer as a start-up setting at least. In my situation, my DDR4 is on 3600MHz default. With an unchanged 1.35v voltage, it is effortlessly able to be configured to 4000MHz. Was tested both with and without XMP+manual/auto timing+manual voltage, it was able on reaching up to 4400MHz and 4333MHz but they are not the limit yet, hence I used my rig on heavy video editing, this is a very useful OC that need to be done plus adding more RAM capacities is an absolute clever step, depending on your requirements. In my opinion, it is not all about who has the fastest RAM on the planet, in competition, no one is gonna stop when one achievement is obtained and that is why there will be always a new one in a short time, but rather chasing all of that on time, you should know what is your target for achieving it based on your needs