Compartmentalized Mind and Berserk

[Strabo]

If a character has Compartmentalized Mind and goes Berserk, do both compartments go berserk, or only one? Can one compartment fail its CR roll and the other succeed and act normally and cast spells? Is it possible to make a Compartmentalized Mind that is not affected by Berserk (for example, Cosmic, Does not go Berserk, +50%). If so, is Only when Berserk, -20% applicable here, if I want this second compartment to only be available when Berserk.

[Sam Baughn]

It isn't terribly clear, but I'd say either rolling for them both at once or separately with only ones who fail being affected is roughly equivalent in value, so call it a no-cost choice when you build the character.

Having one berserker mind and one normal one seems like it should be a straight 50% limitation on Berserk.

[Hide]

As far as I understand, each mind works separately.
In this sense, you should roll berserk as many times as minds you have.

Then, if one of your minds loses control, you must roll a quick contest of will between your minds. The mind currently in control should have +1 to will.

Whoever wins, takes over the body.

Finally, if your all of your minds go berserk, each mind must roll to dismiss its effect. If any of your minds fails, you will roll the "possession quick contest" as well (This scenario is really fun, don't mind me, hahaha).

Now to your questions:

Originally Posted by Strabo

Is it possible to make a Compartmentalized Mind that is not affected by Berserk (for example, Cosmic, Does not go Berserk, +50%). If so, is Only when Berserk, -20% applicable here, if I want this second compartment to only be available when Berserk.

Oh, I can see what you want to achieve!

"Cosmic: Unaffected by berserk", that is OK at +50%.

"Available only when berserk"... this should be -10%. Why? Say, you can willingly go berserk, and (conveniently) get to your senses if your "invulnerable mind" takes over. There are several ways to deliberately go berserk anytime you wish... And if you have enough will you can "easily" take over your body with your other mind, right? Finally you don't need to take an extra maneuver because your other mind is executing a mental maneuver...

Regardless, you will always have to roll the "possession quick contest"... And the berserk mind has a +1 to will for being in control. Seems risky, to me.

Compartmentalized mind is rather expensive.

At this rate, I would rather buy separate advantages to acquire the benefits of going berserk without being berserk (high pain threshold, indomitable or enhanced move score, striking ST...) and acquire the mental strength skill to endure mental stuff. If you want an "expensive" disadvantage, take "phantom voices" and you can play your part as a guy engulfed by the spiral of madness. This should cost as much as "compartmentalized mind 1 + berserk".

- Hide

[Strabo]

Originally Posted by Hide

"Available only when berserk"... this should be -10%.

It is -20% as per GURPS Power-Ups 8 - Limitations, page 16.
Thanks for the answer, I think everything is clear now.