Hardware, as in adjusting jumper settings and stuff like that? I tried the trick where you put a text file into the game folder with modified Glide settings, but I can't say that there was any difference in doing that. As for actual hardware modifications, sorry, I don't have any experience with that. All I know is, most overclockable video cards have fans attached to them for cooling, so I either wouldn't recommend touching anything, or going out and buying yourself a new fan. Considering you have an iMac, however, I don't know if there would be enough clearance inside the case for another fan.
Geez, maybe you should just read a book or something instead.