Thread: Overclock the N900?
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egoshin is offline egoshin
2010-04-23 , 15:19
Posts: 992 | Thanked: 995 times | Joined on Dec 2009 @ California
#3271
Originally Posted by AlMehdi View Post
But wasn't the question how this affect an undervolted OC? I can not say i understand the matematic but shouldn't you try to compare the stock output with the OCd at different VSEL setting?

The stock takes 1.350V on 600mhz and when running 950mhz you could do it on 1.200V. The stock use far less volts on lower mhz which would explain the lesser energy consumption but the OCd use even less than stock.

So does the energy increase more if i am running 950mhz/1.200V comapred with the stock kernel? As the consumption is less i do not think so but i am not an expert on the subject.
The sole goal of overclocking - get a faster N900.

But this depends from multiple factors and if it could be found, for exam, that in proper handling CPU spends less energy with high frequency (just because it runs faster and energy increase is proportionally less) then some things become simpler. Don't forget, somebody can't overclock because CPU instability danger but they want a faster N900 too.

One example - switching between CPU frequencies takes time and frequent switching actually steals CPU performance. The CPU switching itself takes around 30nsec but it looks like some equipment needs to be put on sleep and restored during switch process. So, many frequencies may also steal your CPU performance.

But put all hopes on OC for N900 performance may be not very good, somebody (like me) hesitates OC especially with undervoltage because CPU may be unstable. At least a small research is needed to be sure that it wouldn't corrupt valuable N900 data.

However, the OC experiments are good - nightfire reports that he routinely runs N900 on 500MHz and has 24h-48h usage on moderate work. It is a good sign and it advised me to look into performance vs energy ratio with more attention. Based on my Intel X86 experience I didn't expect that CPU on high frequency may consume power in less proportion than CPU performance increase.
Last edited by egoshin; 2010-04-23 at 15:31.