AGGEMAM said:
Assuming that you have a +4 Int enhancing item, and that you increase Int at 4th and 8th level, and that you are human - the thing goes:
1st - (2+1+3)*4 = 24
2nd to 4th - (2+1+3)*3 = 18
5th to 7th - (2+1+4)*3 = 21
8th - (2+1+5) = 8
9th to 10th - (2+1+6)*2 = 18
Total 24+18+21+8+18 = 89 (if human, 76 if not)
I've always been under the impression that Int enhancing items/spells would not translate into extra skill points. That may be a house rule of ours, or it might have been written somewhere. We've been allowing retroactive increases in skills based on raising Int, but I'm not sure that's technically possible.
The problem is, of course, what happens when the Int-enhancing effect is no longer there. If you take off that Headband of Intellect, it makes no sense for you to keep the skill points that you gained from it. So, you would have to keep track of where those skill points went, and when the effect came off, take away those skill points and put them back when the effect comes on again. That's entirely too much bookkeeping and rife for error/cheesiness. For example:
"What? I need (Skill that I don't have)? I'll take off my Headband of Intellect, thus losing Knowledge (Nobility), since I won't need it right now, and put it back again, and, look, now I have (Skill that I didn't have before)!"
or
"Oops, I'd really like to be able to Use Magic Device, but I didn't put any skill points into it. Bob, hit me with that Fox's Cunning, would ya? Ah, that's better. Oh, and can you hit me with an Eagle's Splendor and a Wieldskill, would you? Great, now I rock!"
Were I DMing, I'd rule that nonpermanent Int-enhancing effects do not give you skill points to use. Semipermanent effects (i.e. from items) could potentially have skills attached to them; a Headband of Intellect+4 that gives max ranks for the user's character level in two Knowledge skills would be perfectly fine, and would involve only minimal handwaving ("They're connected to the Akashic Records/God of Knowledge's database/whatever, and as I go up in level, I can better make use of the information!").