Introduction and Definition
A "utility high" is defined as a high slot on an EVE combat ship that is not devoted to that ship's primary weapon groups. The ship's primary weapons are defined as those for which the ship has the largest number of slots: either missile launcher slots or turret slots.(1) Almost every ship has at least one utility high, and a few have as many as three utility highs. Often, you are given direct clues in the ship's description or among its bonuses for what the developers intended that high to be used for. For instance, on Recon, Covert Ops, and Black Ops ships, it's intended that one of the utility highs will be used to fit a cloaking device.
Other times, though, it's not clear at all. Many players struggle with the choices available to them for what to put into their utility high slots. The purpose of this guide is to list many of the popular options and the advantages and disadvantages of each.
One more thing: don't neglect the advantage conveyed by fitting a module in a high slot, but keeping it off-lined! For instance, a PvE Drake will often have an off-lined Small Remote Armor Repair System in its single utility high slot. The purpose to this mod is to repair drone armor damage between missions. You don't need it very often, but when you do, you can off-line a Ballistic Control System, online the repper, repair your drones, then take it back off-line and put your BCS back on-line. PvP ships can fit an off-lined Salvager for use between battles and use it in a similar way. The disadvantage here is the long wait to cap back up after on-lining a module, but if you're sitting and waiting for something to happen anyway, this cap reduction can be managed.
Utility highs are designated as "offensive" if they are primarily useful in PvP ships, but some will add value to PvE ships as well.
Neutralizer. Best used on: all battle cruisers, Minmatar battleships. The purpose of a neutralizer is to reduce the capacitor of the ship that you are fighting. If the ship is using active defenses -- or even better -- cap-using guns like lasers, this will go a long way toward throwing a fight in your favor. In fleet scenarios, massed neutralizers are deadly to the ships they are used on, and even small or medium neuts can cap out much larger targets such as carriers or super-caps if they are used intelligently. Neutralizers are best used offensively in pairs, and for this reason, the most deadly neut-fitted ships are the Hurricane, Tempest, and torpedo-fit Raven. Each often fits a pair of neuts in a PvP scenario.
NOS. Best used on: Interceptors, other frigates. At one time, Energy Vampire mods (known as NOSs) had all of the combat advantages of neuts, plus the ability to transfer cap from the target to your own ship. They still do... but only if your cap -- measured as a percentage -- is lower than that of your target. As a result, in today's EVE, NOSs are only of particular use to ships that run highly cap-unstable. This fits most interceptors and many other attack frigates. Usually, a single NOS will be sufficient to provide just enough power to keep the attack frigate's afterburner or self-repper running for 30 seconds longer... which can be the difference between winning the battle and losing it.
Smart bomb. Best used on: Battleships. The so-called "smart" bomb is nothing of the kind. It is simply an area of effect weapon which detonates in close proximity to the ship. Anything caught in the blast radius (usually between 2.5 and 8.5 kilometer's from the ship's hull) takes damage of the same type as the smart bomb. Offensively, smart bombs are most often used for ganking. A single smart-bombing battleship can make very short work of frigates and mining barges if it dives into their midst. Armageddons are popular in this role. It is also sometimes worthwhile to use a bubbler to force enemy ships out of warp in a given location... where one or more smart-bombing battleships are waiting. Using EM smart bombs on a close formation of heavily EM-tanked Abaddons is a popular use of this tactic.
Auto Targeting System. Best used on: strategic cruisers, battle-cruisers and above. This is probably the most-overlooked mod in the game. A simple Auto Targeting System I uses only one unit of power grid and only one unit of CPU... and lets you target two additional ships. The Tech2 version uses much more CPU, but lets you target three additional ships. This is a particularly huge boon to strategic cruisers, which generally can only target five ships. It will annoy you from time to time by using those extra slots to lock people who are attacking you, but even this can be a boon. One of my favorite Falcon fits uses an Auto Targeting System to get right to the heart of the matter of who to jam... ;-)
Remote Armor Repper. Best used on: anything. In an offensive scenario, particularly for shield-tanking roaming gangs, one or two ships in the gang should fit a remote armor repper. Even if that module is normally kept off-line, it can be brought on-line as needed to keep ships that take armor damage repaired, and then taken back off-line when no longer needed. A gang of cloaky bombers behind enemy lines should all fit one remote repper. Three out of four such reppers should be remote armor reppers; the remainder should be remote hull reppers. And though it was a more common tactic two years ago, you also still very occasionally see "RRBS" gangs: gangs of battleships fit with weapons and a single large remote armor repper in their utility high.
Remote Hull Repper. Best used on: bombers, other Covert Ops, roaming ships. See above, under Remote Armor Repper. A cloaky gang behind enemy lines should have one or two ships fit with Remote Hull Reppers to keep everyone (including any drones that are along) in top form while unable to dock or effect repairs in any other way. It's also sometimes handy to have one along if a roam is going to go far behind enemy lines with few or no docking opportunities. You don't need a lot of Remote Hull Reppers, but one or two in a fleet can be vital!
Empty slot. Best used on: pure DPS boats. An empty slot, placed in the midst of a ship's guns, will make an effective heat sink against overheating using the Thermodynamics skill. An empty slot will often take more heat damage than a utility mod, particularly on strategic cruisers. If you're going to fit an empty slot, then you'd better plan to overheat often, and remember to put this empty slot in the middle of your fitted guns, not on one end or the other. While overheating is supposed to "wrap" from the first module to the last and vice versa, it often doesn't.
Energy Transfer Array. Best used on: battleships. If you are roaming as part of a large gang with "cap buddy" Logistics ships, a few of the battleships should carry an Energy Transfer Array. This allows them to act as emergency cap buddies for these logis. They can also be handy for many of the Amarr battleships that are not quite cap-stable unless they are trading cap back and forth with a partner. You most often see this latter tactic being used in POS bashes using Armageddons.
Salvager. Best used on: cruisers and battle-cruisers. If nothing else, a Salvager (even an off-lined Salvager) can be valuable to a quicker ship in a PvP scenario to pick up a little extra ISK. ;-) And an off-lined Salvager placed in the middle of one's guns (on a PvP Drake, say) makes a very effective heat sink for overheating.
Core Probe Launcher. Best used on: Vagabonds and other 0.0/WH hunter-killers. In sovereignty 0.0 systems and in wormholes, most of the action takes place in non-celestial sites that can be scanned down. Some of these can be discovered with the recently-buffed ship scanner, but many more require a few Core Probes in order to find. A null-sec fleet behind enemy lines can sometimes benefit from at least one ship fitted with a Core Probe Launcher to seek out these sites. When PvP hunting in wormholes, though, this is vital and should be spread to at least 10% of the ships in the fleet (in case of losses).
Cynosural Field Generator/Covert Cynosural Field Generator. Best used on: Recons. This is definitely a specialty need. Still, if you have a large roaming gang and you have the ability to bring in capital ship support, it's smart to have the logistical capability to do so available. Most Recons have such poor DPS that it's often useful to fill their high slots with nothing but utility high slot modules and leave the DPS to the other ships. Obviously, if you intend to fit a cyno generator, make sure you have both fuel and you keep track of the jump range of the ships that will be coming in...
Utility highs are quite useful in PvE scenarios as well.
Drone Link Augmentor. Best used on: battleships, particularly the Dominix. The DLA is hugely CPU-intensive, but the extra 20 kilometers of drone control range it supplies are a boon to slow-moving battleships, particularly facing longer range frigates that can appear in L4 missions and wormholes. This mod is not a good fit for incursion-running. A long-range drone in an incursion site is a dead drone. In these sites, keep your drones close.
NOS. Best used on: laser battleships. In incursion and wormhole PvE, laser battleships (such as the Imperial Navy Armageddon, for instance) sometimes need just a little bit of extra cap. A single large NOS can provide this by using it on close-range battleship rats that the player isn't targeting at that particular moment. As of this writing, all rats have one unit of cap, and their cap is perpetually at 100%, so they will always provide you with a full measure of your NOS's capability. I once went through almost an entire Incursion mom site with a large NOS attached to the mom providing me with the power my GNI needed to help destroy her. ;-)
Auto Targeting System. Best used on: strategic cruisers, battle-cruisers and above. As noted above, a simple Auto Targeting System I uses only one unit of powergrid and only one unit of CPU... and lets you target two additional ships. The Tech2 version uses much more CPU, but lets you target three additional ships. This is a particularly huge boon to strategic cruisers, which generally can only target five ships. The ability to target two or three additional rats is quite handy! Finally, ships that intend to both destroy the rats and salvage the wrecks can benefit from a few more locked targets to make this easier.
Energy Transfer Array. Best used on: battleships in incursion or wormhole fleets. As noted above, in a fleet with Logistics support, having a few battleships in the fleet mount Large Energy Transfers is vital to the overall health and safety of the fleet. In addition, again as noted above, many PvE battleships can benefit from trading cap with a similar buddy. Incursion fleet Nightmares, in particular, will benefit from this tactic.
Tractor Beam. Best used on: Marauders. PvE is usually all about killing rats, then looting and salvaging them. Low-effort PvE Marauders such as the Golem will nearly always have one tractor beam fit to pull in wrecks for this important part of the process. ;-)
Salvager. Best used on: Marauders, other battleships. In a similar vein, the very same Marauders will also have a Salvager or two to salvage the wrecks the tractor beams pull in. But even on a non-bonused ship like a Raven, a Salvager can make L4 missioning a little less dull. If nothing else, pull in and salvage the more valuable battleship wrecks and leave the rest behind.
Remote Armor Repper. Best used on: battle-cruisers, anything with drones. A typical L3 mission Drake will have a single small armor repper fitted that the pilot can use to keep his drones repaired during missions or once the mission is over.
Core Probe Launcher. Best used on: anything in null-sec or wormholes. PvE ships that wish to snoop around null-sec or wormholes looking for sites to run can greatly benefit from carrying their own Core Probe Launcher instead of relying on a second ship to do this scanning. Though the probes will be unbonused, usually PvE scanning is not particularly time-critical, so it doesn't much matter if it takes you a couple of extra minutes to find the sites. Still, many wormhole corps (for instance) will use dedicated scanners for this job, so this is a much less vital choice in those scenarios.
Finally, some utility high slots are purely defensive and can be used in a variety of scenarios.
Cloaking Device. Best used on: Recons, CovOps, various hunter-killers. Fitting a cloaking device on a ship is a decision that should be made with a lot of forethought beforehand. Even off-lined, the cloak will greatly reduce the ship's Scan Resolution, and there is a substantial targeting delay that has to be waited out for most ships after the cloak is turned off. However, used in the right situations, a cloak can confer tremendous advantage. Recons, Stealth Bombers, and Black Ops rely on their cloaks, of course, for surprise attacks. But even low-sec and null-sec hunter-killers, such as Vagabonds, can benefit from a cloak to mask their presence before striking.
Smart bomb. Best used on: Battleships, Recons. The so-called "smart" bomb is nothing of the kind. It is simply an area of effect weapon which detonates in close proximity to the ship. Anything caught in the blast radius (usually between 2.5 and 8.5 kilometer's from the ship's hull) takes damage of the same type as the smart bomb. Defensively, smart bombs are used for drone clearing efforts, particularly damage or ECM drones surrounding friendly support ships such as logistics or Bhaalgorns. Recons sometimes use them to clear ECM drones off their own hulls as they ply their trade.
Auto Targeting System. Best used on: haulers (yes!). The auto-targeting system can also be used defensively. Since it will automatically target those that take hostile action against you, the chirp-chirp-chirp as it starts locking someone can be a valuable audible clue that a high-sec hauler should start taking defensive action... because someone has selected you for a suicide gank.
Neutralizer. Best used on: anything. Neuts are usually offensive modules, but don't neglect their defensive uses! Large ships are often at threat from smaller tacklers, which -- while tiny and hard to hit -- are often quite cap-constrained. A single medium neut on a Vagabond, or even a small Tech2 neut on a Drake, can go a long way toward reducing the threat of these small targets. You don't even have to try to get into neut range yourself to use them. These tacklers will often get right up next to you, putting them well within a defensive neut's range.
A point defense weapon. Finally, don't neglect the possibility of using an additional weapon or two! Though a lot of players don't think of it, virtually every ship with a utility high slot will allow the use of one or two "off-bonus" weapons in those slots. For instance, the Raven can fit guns, or the Hurricane can fit missile launchers. Often, you won't have the power to fit a particularly powerful weapon in these slots, but even a small Standard Missile Launcher, Rocket Launcher, or small turret can be used as a point-defense weapon against frigates and drones... or can add directly to DPS if you feel like getting close enough to your target.
This concludes my guide on utility high slots. I hope it's been useful!
EDIT (26/Jan/2012): The original guide, as published, omitted smart bombs. They have been added, both for their offensive and defensive uses.
EDIT (13/Feb/2012): Added a short note with regard to utility cynos.
(1) Four combat ships will not be discussed since their primary focus is not that of inflicting DPS: the Curse, Pilgrim, Cruor, and Ashimmu.