How Much Battery Does Undervolting Really Save?

Hey hey. I just undervolted my t7200 from 1.375V to 1.000V at 2ghz. I stress tested for 2 hours with no negative affects. At all. I've noticed my fans barely turn on anymore and my CPU temp is always a goo 7-10 degrees C lower. I haven't tried out comparing battery life. What do you think the difference will be? Will it be major? Or is it going to be minimal? I've also read the guide to cool down your notebook which I almost live by. My notebook isn't too hott anyway, but the cooler the better!

Last thing, I can't find a guide to optimize battery life. I see the guides that tell you how to care for your battery but not battery life. Any ideas?

 

I can't believe you cancelled your 1330 for the Vaio!! Must've been a price issue..

 

Nah, I'm just not patient... at all... I also liked the way the Vaio looked and it came with Vista Business. And the switching between the 2 graphics options... Masterful... I adore it. So many things I love about this laptop.

 

The issue will not really be battery life, but how cool the notebook runs under load (which you have already noted) As long as the chip is stable, it's great to run at a lower voltage.


The problem is that Intel has locked the lowest multiplier step on their chips, (you can't change the voltage; it's stuck at .95) therefore you won't save anything while on battery because the chip will default to it's lowest step to preserve juice (that is unless you have it running at maximum speed all the time for some reason) When you are really pushing the notebook, or letting it ramp up to full speed, you will likely be plugged in, making battery an non-issue.

 

When my laptop is running on batteries its always down clocked down to 1.0Ghz. So I haven't done any testing for battery life. I was after the reduced wattage and temperature, and didn't really care about battery life since I'm running a DTR.

You can always set your VIDs back to normal, take measurements and then down volt again and do the same if you really want to know.

 

Hmm so basically battery life won't be affected much since Intel locks it at .950V? Is that what the chip defaults to when reduced to 6x speeds and running on battery? If so I am gonna be pretty disappointed...

 

Yes/No, if you are testing plugged in you lower heat. I am confused when unplugged already undervolts lower than you have? If on battery you run on the higher performance which can be set up you will save. Take your higher voltage and subtract by the lower voltage. That will give you the difference, what ever it is there is much more than CPU running so I am thinking about 5 to 10 minutes!

 

I undervolt my cpu from 1.175V to 0.950V, on 12x at 1.6Ghz.
More than 20 degree C on a long full load.
Now never goes over 60; before it toped over 80 and I got worried so I stopped 2xprime95

 

Yes, 6x is indeed locked at .950V. If you are running in dynamic switching and doing cpu intensive tasks at higher clock rates, you will see a savings.

 

if u wanted to save battery life then u shudve gotten the 1330 as the new santa rosa chips save quite a bit of battery life without undervolting so there might have been a difference saved with the undervolt.

if u want to save battery life and dont worry much about speed, you can use RMClock to limit the CPU to running 1ghz at the 6x multiplier all the time.

 

So far, I not convinced that Santa Rosa is giving power savings.

Undervolting the Core / Core 2 series CPU only extends battery life if the CPU is heavily utilised while running on battery. If the computer is only under light load (or locked at the lowest speed), then there will be no power saving.

John

 

I disagree John, it will give you a power saving because while yes if it is used lightly the battery life will not suffer alot, however when opening programs you usually find the CPU going over its minimum speed for a while, this does take up battery life. if u undervolt and limit the CPU to its minimum like me, you can extend battery life even if it is by a few minutes.

as for santa rosa, I have noticed between the reviews of previous HP laptops and the new models that the battery life has improved even if it is by a small amount, the difference is still there.

 

I agree with you John. The split second where the core actually spikes is so small it's not noticable. I wish Intel hadn't locked the voltage at 0.950v. This takes the fun out of the undervolting.

 

Well, any time you are putting out less heat, you are consuming less power. Why don't you do a battery run-down test and see for yourself?