On battery and CPU performance

I'm now using Sony Vaio SR series, with Core 2 Duo T9400 , 2.5ghz. Everything is fine when it run with AC in. On battery, the CPU can only get 1.68ghz at maximum. I've check Windows Power Option and tried to set to High performance (with setting min/max =100% for CPU usage) but it didn't help. Does BIOS automatically lock the CPU's frequency on battery mode? Anyone can help?

 

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Are you doing anything cpu-intensive?

 

I have to run virtual machine on my laptop because my course work does require it, and it's significant slow when running on battery. You know, it's inconvenience for finding an AC outlet in classroom or in public place.

 

check the fan speed option also in advanced power

make sure fan speed is set to 5 or the highest setting in battery mode

i believe the default is like 3 which will throttle cpu

 

Thanks but I can't find fan speed option in advanced power settings. I'm now using Windows 7 pro 64bit.

 

ahh yes they removed the fan speed option for win7

so its all controlled by the min/max settings under advanced power... make sure you have 100% for "on battery" because mine is default to 80%

also check the graphics settings to make sure they are at max performance on battery as well

 

As I said above, I set min/max to 100% on both battery and plug-in.
I forgot to mention that in Ubuntu the processor can run at its top speed (2.5ghz) then I doubt something is different in Windows. Any idea?
P/S:By the way, thank you for your suggestion!

 

Well my old SZ would throttle CPU and GPU on battery no matter what. I installed NHC notebook hardware controls to override sony's settings it seemed to work. But I was running Winxp not Win7

My new Z11 doesn't seem to have that problem

 

there are certain models that does this "CPU speed capping" when using the battery mode. This also happens on VPCF1 series where the CPU speed is capped at ~995 MHz when running on battery mode. This is to prevent the system from using the electric power more than the battery specification. Other models that has this are FW and AR Series.

Yes it's also true the Z11 series doesnt exhibit this.

-jog

 

Ahh that is correct about the battery output I almost forgot!

My old SZ would also throttle power whenever I would plug in to charge up battery between 0 and 85% but would give me full power once the charging passes 86% because it would enter a trickle charging state that used less power.

Drove me crazy until I figured it out. I believe some Dell laptops have the same issue and they were able to solve it with a higher rated amp power cord charger.

But ya on battery power you won't be able to exceed what your total component usage can handle so if running LCD + processor + graphics card all sane time and battery is only rated for a lower output you gonna get throttled. Maybe there is a higher rated battery for your SR?

 

The main problem is overheating. The faster you charge or discharge a battery, the hotter it gets. If you remember back to 2006, there was a rash of numerous battery overheating problems with Sony batteries used in various manufacturers' laptops, including a few instances of fires. Sony ended up having to recall millions of laptop batteries used in Dell and Apple laptops. Ever since then, they've been really conservative about charge & discharge rates.

If you do manage to successfully defeat the throttling, pay attention to your battery temperature.

You're also likely to wear your battery much faster.