Thread: Overclock the N900?
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nightfire is offline nightfire
2010-04-19 , 16:40
Posts: 310 | Thanked: 383 times | Joined on Jan 2010
#3137
Originally Posted by titan View Post
This is wrong and misleading information!
The min. freq. is the one used for low load, like updating widgets, decoding MP3s etc.
In his case the permanently high load at 1GHz probably killed the battery
but the brain dead 850 minimum is a sign of irresponsibility and how little
he understands this device.

If we had access to the core temperature it would be one factor that determines
the damage of the SOC.
Several people here mistakenly believe that this sensor value would indicate
the CPU temperature. It does NOT!
If your device gets really hot, than it's a sufficient, but not a necessary sign that
you're doing something wrong.
So don't just rely on the temperature.

If you believe temperature doesn't matter, please perform an experiment
and bake your N900 in an oven @200C. It may void your warranty, however...
But, rendering said widgets happens 2 or 4 times as fast, limiting the amount of time spent off idle. Sure, it uses more power and thus creates more heat. But nowhere near the amount that running anything significant at even 600mhz does.

That is, playing an mp3 at 850mhz means 5% on CPU, 95% idle. Heat is 5% of maximum dissipation @ 850mhz, so say 3W * .05 = 0.15W.

At 250mhz, it means ~15%, plus the occasional bout up to 850mhz anyway. Say the processor draws 0.5W at full load @ 250mhz. 15% of 0.5W = 0.075W, for a difference of 0.075W thermal dissipation. Hardly anything to worry about.

It may reduce battery life slightly, but I bet 0.075W pales in comparison to the rest of the power draw (radios, DSP, amplifier, etc).

Compare that with running an intensive process at 600mhz. Assume the processor draws 1.5W at this speed. 1.5W @ 100% for 10 minutes represents 0.25Wh of heat dissipation. That's the same as a 5% duty cycle at 850mhz for almost 2 hours. 10 minutes at 600mhz is ~10 times worse.

Of course there is the argument that even though the heat dissipation is low, the temperature changes are more rapid and may lead to premature thermal failure anyway..
Last edited by nightfire; 2010-04-19 at 16:45.