Originally Posted by seanmcken

when i overclock the n900 to 950 or 1100

the battery of phone sucks like a thirsty guy drinking water and other phones with 1 ghz or more than that gives good battery life so wat's exactly reason behind this?

Originally Posted by pichlo

As a rule of thumb, power consumption of modern electronic devices increases with the square of the frequency. That is, if the frequency increases 2x, power consumption increases 4x. Frequency 10x, power 100x, etc. The reasons are several and, from the way you ask the question I suspect they may be a bit too technical for you, but simply put, tiny components within the chips draw tiny jolts of current on every status change. The overall power consumption is a sum of these tiny jolts. Of course, with an increased frequency you have more of these status changes per any given amount of time.

There is a flip side. With an increased frequency, a CPU can finish any given task quicker and go to sleep sooner, so a small increase of the CPU frequency can actually reduce the power consumption. It is generally agreed on this forum that the optimum frequency for the N900 is 800 MHz (someone please correct me if I'm wrong). However beyond a certain point, the power increase caused by an increased frequency outweighs the positive effect of more sleep and the battery drag goes up.