For battery life !

Looking to squeeze the most out of my battery. Right now I'm underclocked to about 2200hz instead of the default 2900 or so. This definitely improved battery noticeably but I want to take it 1 step further. Looking to undervolt as well.. Is there an app that is just head & shoulders above the rest for under clocking and undervoltng? Also I'm wondering if underclocking the GPU is a route to go as well for saving some battery..

Thoughts? Sorry I'm rambling