ohh, shit, I totally left out a zero. My bad.
it is .01 per point, not .1
My bad, was at college and not thinking properly.
I just ran the numbers for immortal shoulders, and they would have given 300 regen, which is farrrrrrr too much. They actually give (a guess, based on eyesight) about 90 mana regen.
[.1 +(INT *.01)] * (1+REGEN)