“You've been pushed around long enough! With the Nerd Rage! perk, your Strength is raised to 10 and you gain 50% to damage resistance whenever your Health drops to 20% or below.”— Fallout 3 in-game description
Whenever your Hit Points drop to 20% or below, your Strength is raised to 10 and you gain 50% to damage resistance. This stacks with other perks, and applies regardless of clothing, which makes it still useful even if you wear heavy armor, as it can help maintain your DR even if said armor is damaged or broken.
Interestingly enough, combo of 35-40 DR protection (average Power armor or 100% condition Combat Armor) and Nerd Rage effect allows to reach max DR (85 percent DR), which means only 15 percent of damage points affecting health; which is four time less, than 60-65 unresisted damage percentage, average for heavy armor user. In the same time, it is possible to replenish health in small portions by consuming food or water, without stopping the effects of Nerd Rage.
Whenever your health drops to 20% or below, your Strength is raised to 10 and your Damage Threshold is boosted by 15. As in Fallout 3, this effect stacks with similar bonuses, and applies even if you're naked or your armor is broken; you merely need to meet the health threshold.
Notably, the Courier's base health determines the trigger for this perk. Bonus HP from other sources such as Buffout or the Thought You Died perk will not raise the threshold.
Unlike previous versions of Nerd Rage, due to the diminishing returns of Damage Resistance in Fallout 4, one should no longer consider the primary benefit of Nerd Rage to be the additional damage reduction, although it does help in a pinch. Instead, the slow-time effect is the primary defensive (and offensive) mechanism, lasting about as long as a normal (unmodified by Chemist) dose of Jet.
The effect does not last as long as you are below 20%, in a break with previous versions of the perk.
It is possible to repeatedly re-trigger the effect by healing yourself above 20% and then taking enough damage to drop back down below 20% health.
If time is already slowed from a Jet-based drug, then you won't get much extra benefit from the slowed time, though you still gain the damage and damage resistance bonuses.
There can be buggy interactions if this perk is triggered during VATS (giving you the bonus damage and resistance but not the slow-time effect), though re-entering and leaving VATS tends to help.
Because Fallout 3 has a DR cap of 85, most or all of the 50 DR bonus may be ignored under certain situations (such as combination of fully fixed Medical Armor, Med-X provided by the armor and Med-X injected separately)
Similarly, while Fallout: New Vegas does not feature a similar cap on DT, 20% of pre-DT damage is guaranteed to go through, regardless of how high a player's DT is. As such, in certain situations an increase in DT may yield little to no benefit.
If you're having difficulty eyeballing how much 20% of your health is, this is the same amount of health you need before you begin to hear your heart beating.
PCXbox One In Fallout 4, Nerd Rage may stop activating when health drops below 20%. This issue can be temporarily remedied by bringing up the Pip-boy then closing it while your health is under 20%. It is not currently known what causes the issue. (Bug is confirmed to occur with all ranks of Nerd Rage). [verified]
This problem can be fixed by removing and adding the perks via the following console commands in order:
player.removeperk 00065e38 (skip if you don't have Nerd Rage at rank 3)
player.removeperk 00065e37 (skip if you don't have Nerd Rage at rank 2)
player.addperk 0004d886 (adds Nerd Rage rank 1)
player.addperk 00065e37 (adds Nerd Rage rank 2)
player.addperk 00065e38 (adds Nerd Rage rank 3)
PC In Fallout 4, the slowing of time may sometimes be cancelled by chems such as Jet. It sometimes also happens with V.A.T.S, giving you real time speed in V.A.T.S.[verified]