Just to re-iterate..
Download app... It's not a free app.
Install it
open it - hit the recommended button.
Now, you can have a few different experiences.
The main screen that comes up is for setting the speed sliders of your phone, if they can't be moved (mine weren't), then make sure first to close the program and go an find the Super User program in your program list. Open that and make sure that SetCPU is marked as a program in there. Then return to SetCPU.
If the sliders can be moved now then you're ready to go. If not, then try disabling Perf Lock by hitting menu, and 'disable perf lock' that should help.
Now I've read that some ROM's only allow certain levels of customization in speed, so don't fret if you can't get to 800, you shouldn't anyway!
All the literature on this site said we could go between 710 and 786, but after that was asking for troubles. you could freeze your phone or worse, brick it.
I set mine at 710 and 528 for low. apparently 528 is the high mark where the phone was before, so under that number and your underclocking your phone.
Th important thing is to set profiles.
so, go into the profles tab and create a few... here's mine from reading about 40 posts last night.
Main Window = 710/528
screen off = 480/245
charging full = 710/528
temp = 43 degrees - slider at 100% and 480/245
Other than the temp, leave the priority sliders at 50% for the rest
you'll understand when you see the program.
I left all profiles, including main set to 'ondemand', this lets the phone scale dynamically between the values I present, performance - the other option, pinns the speed at the top mark. it'll drain your battery and can over heat your phone after a while
click the set on boot button on the front page of the program and restart your phone.
you can of course go crazy with over clock, but it'll kill your phone and battery and then it's all moot anyways.
710 seems like a great tradeoff.