I've recently bought a second hand half an year old macbook air. After a week with my mac, and being a 20-years veteran windows user, I must say, I'm extremely impressed. Running a windows 7 on my parallels, coherence mode, with visual studio, office, and whatnot running. and not feeling a slight lag, and all of that with 2gb ram... unbelievable anyways... battery life was 5 hours, which is impressive but... i did wish for me. so i search up and looked for an undervolt possibility... and tracked down coolbook. im a programmer so i thought... 'hey i can do that myself'.. so i managed to find something similiar, and did it... but - throttling didnt work so well, and i could only manage to undervolt it to 1.000v, which is nice but not enough. so after two days of trial, and a beginning fear of screwing my beloved mac, i decided to purchase coolbook for 10$ and, man, i got a good surprise... i underestimated it, i saw from 9:00am, with visual studio, office and google chrome running, and im a heavy-user... with 10 tabs and a google chrome open on my windows vm. so from 9:00am, to 2:00pm, i've been using the mac continously, battery is now on 38%... meaning, i've used 3/5 of the battery, for 5 hours... battery will go for 8 hours, meaning i've got 3 extra hours out of coolbook.. i was really sceptic about coolbook and didnt want to 'waste' 10$ on an undervolting program.. but... i gotta admit it was worth it... alot.. as a student which doesnt want to mess with outlets and stuff, its perfect. 8 hours of continous heavy-load work... AMAZING. (not to mention the comp is cool indeed) of course, im running my macbook at 0.925v for all frequencies, which are the lowest settings. im more than happy btw, its really important to be EXTREMELY careful when playing with these settings - it could damage your mac. btw, macos > windows, by some levels.. from a mac hater to a mac fanboy?