using a lower clock while sleeping wont really help the batt life as even at low freq the procy consumes same amt of voltage...infact it may make it worse due to the constant scaling. read this
[TWEAKS][UPDATED 26/04/2011 - Flashable .zips] Performance and battery tweaks - xda-developers
specifically this part from the above link
Battery life increase for Dummies
Do you want some extra juice in your battery life? Does it seem that you lose your battery too fast? Then you came to the right
place.
Over the time I've gathered some information about our battery and while this isn't 100% proof (because all of us use the phone for different purposes)
I think it's most accurate:
The myth of having the lowest possible frequency on your CPU while it's asleep:
Having the lowest frequencies (122 or 248) set up, it's not good. Our phone doesn't change voltages while underclocking or overclocking (as far as I know overclocking
doesn't change voltages as well) so, and only talking about underclocking, having such a low frequency is bad for your phones battery and performance. For the battery
that's because it takes longer to wake up from sleep and the time that the cpu takes to scale from 122/248 to maximum instead of using it for processing power eats
your battery away. About the performance hit, well that's pretty obvious and it takes longer to idle up, so again, more battery drain.
Having read about this the last few days actually running in Performance Governor is pretty beneficial to your battery: it wakes up faster, it performs every task faster,
then it idles up faster. Yeah during "sleep" time having 122 frequency or 806 it's the same thing because it's not using its power for anything, it's just there idling.
In any case what I always suggest is TEST it up and see for yourself. If you don't want to run with Performance governor at least run with 480 minimum frequency, it really helps.
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Why do you run with auto-sync, gps, wifi, 3G, firewalls, anti-virus, background apps killing your battery? That's bullshit. Most of you complain that your battery doesn't last as long
as it should...well that's not ROMs fault, I've been running with CM7 buils since the first builds and I never, ever, ever had battery problems even when everyone complained. Why?
Because I'm careful. If you don't need auto-sync at that time, disable it...if you don't need gps, disable it and so on. I don't know why people leave this stuff on even when they are not
using them. Firewalls? That's bullshit as well along with anti-viruses. They eat up your resources for nothing. Same goes for background apps that eat it up. Google Maps = bullshit. If
you used it go kill it after you're done with it. Same with Music app. Kill it after you've listened to your 1315618 songs. But DON'T use task killers. I can't repeat this enough, just
DON'T use them for your own sake. Same goes for 3G...just don't enable it all time if you're not using it.
No Live Wallpapers as well, nor 3D app drawers, these blow your battery away easily without you knowing how or why. Don't bother tuning your brightness down...you have a device, and
that's to be used. Why buying a mobile for 200€ and not using it's screen propely? It's there to be used, full brightness looks better, it's not by decreasing it down and hurting your
eyes that you'll get 21564561 more battery hours.
.. So plz suggest which rom will be better..