stoked did a mathed section on this a while back, cant remember the epp number, but no 2 does not = 2x the bonus
With fervent apologies to Wishstone, Supreme Goddess of the Forums, Wielder of Ye Olde Mighty Banhammer o' Doom, and Supplier of Epic Cookies... (I will sacrifice a Windows Vista desktop on her altar later...)
Since there seems to be some confusion (How? I do not know...), here is the information contained in the link from above...
Originally Posted by BigRedJedi
How did this end up in the Art of STO Forum? LOL
In any case, CrustyMac is right about consoles with a numeric modifier (example, Weapon Power Engineering Consoles, or Phaser Relays, or what have you). So, if you have three +7 Weapon Power consoles, you get +21 Weapon Power, etc.
For other types of consoles, especially the +% ones, it isn't so much that there are 'diminishing returns', as each console (particularly, Armor consoles or the less-commonly used Shield Regeneration booster) will add its full value to the formula that is used to determine a final value.
For Armor Consoles (as the primary example of where the 'appearance' of diminishing returns appears), the formula used to determine the final resistance value is: 1 - (100/(100 + Resist value)). The Resist value is the total, combined value of all the sources of damage resistance on your ship. Thus, for example, if you have a single +35 armor console, you will have about a 25.9% resistance against that energy type... if you are a Cruiser running 4 of the same +35 armor consoles, your damage resistance improves to 58.3% (so, adding three consoles only slightly more than doubled your final resistance), thus, you have the 'appearance' of diminishing returns, but, each source of resistance IS adding its full value to the formula that determines your final value.
For the other 3 types of +% consoles:
EPS Flow Regulators stack linearly with each other, but all modify the baseline power transfer/regeneration rate (5 Power transfer/regen per second), thus, if you have one +105% EPS Flow Regulator, you will boost your power transfer/regen rate to 10.25 per second, adding a second +105% would improve your rate to 15.5 per second, etc.
Shield Regeneration Consoles all modify the base regeneration rate of your currently equipped shields, thus, if you add a +10% regen console and your shield has a base regen rate of 100, it will improve the base regen rate to 110 (which is then subsequently modified by your current Shield Power level, to determine your final Shield regen rate).
The Field Generator Mk XI (+35% Shield Capacity) DOES NOT STACK... You can never benefit from more than one of these.