Among the ways in which Bungie has tried to expand Destiny 2 with the new Warmind DLC is with a dash of mystery. The Override Frequency is one such example, as they serve as a post-campaign objective for players to embark on. But the game doesn't provide a lot of information about what they are, how they work, or where to find them--here's what you need to know, as well as the potential Exotic weapon reward, Sleeper Simulant.
Override Frequencies aren't of concern until after you finish Warmind's story, which isn't especially time-consuming. Knock all of those missions out along with those you get from Ana Bray, your new handler/vendor on Mars, and you'll begin to acquire a new type of consumable item called a Resonate Stem. These are acquired only from certain activities, including Patrols, Public Events, Adventures, and possibly by eliminating high-value targets and completing Lost Sectors.
However you obtain them, once you've collected four Resonate Stems, you can combine them in your inventory to create an Override Frequency. There are numerous possible versions you can get, but there are no clear instructions about what to do with it. The description appears to be gibberish--for instance, you might get one that reads "CB.NAV/RUN.()Futurescape.Dock.Garage." In fact, these serve as hints telling you where you need to go.
Specifically, it's the text that's not in all capital letters that you'll want to pay attention to. The first portion of our example, Futurescape, directs you to an area labeled on the map. From there, you head to the dock and then to the garage. When you get to the location your item leads you to, you'll find a floating object (which looks like two inverted pyramids stacked on top of one another) that essentially functions like a locked chest. Provided you've gone to the right location, the Override Frequency you have will unlock the node. You can be sure you're in the right place both because you'll see the "Collect Loot" prompt and because you'll hear music coming from it. You can bump into these nodes at any time in Warmind, but only once you have the correct Override Frequency can you open them.
When opening these nodes, you'll get your hands on rewards like engrams and shaders. But opening them is part of a larger, overarching quest that you can keep track of with Ana. It's unclear at this point what completing all 40 of the nodes gets you, but players have reported receiving the Sleeper Simulant--an Exotic linear fusion rifle--after doing 15 of them. However, you need to get the quest for Sleeper Simulant in order to track progress for that, so you may want to wait to cash in your Override Frequencies until you get your hands on that.
Warmind is out now on PC, PS4, and Xbox One, offering a new campaign set on Mars along with new Crucible content and gear to acquire, as well as a new horde-style activity and a Raid Lair. This was all accompanied by a new update that makes changes to Exotic weapons along with a wide range of improvements.
Info from Gamespot.com