Optimizing i7 Battery life, ideas?

Here a bit of summary of how to enable some advance power plan settings, the highlights are disabling the core parking override and max % of unparked cores.

-Windows by defaults keeps at least one logical core active per physical processor core. With the nehalem architecture parked cores consume almost no power.
-Also keep in mind if you set max unparked cores to 50% it may still activate all cores because 50% of 8 hyperthreaded cores is 4.
-You can use resource monitor to see if cores are parking
-once you've done the registry tweaks below you should have some extra options in your advanced power plan settings
-Setting you power plan back to defaults nulls you the changes to it is harmless and reversable if you are careful
-If you are not comfortable making registry changes don't do this as you can really screw your computer up, if you mess up the wrong things in your registry



Open Regedit (type regedit into the startmenu search box)

Expand location to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\54533251-82be-4824-96c1-47b60b740d00

In order to enable some advanced power plan settings you will have to rename the REG_DWORD "Attributes" to "_Attributes". This one it own does not change how your computer runs, it simply adds an extra option into your advanced settings for each power plan

Here are the relevant registry keys:
0cc5b647-c1df-4637-891a-dec35c318583
lets you set the minimum number of unparked cores (I set this to 25% for power saver)

3b04d4fd-1cc7-4f23-ab1c-d1337819c4bb
turns on additional processor throttle states, caution this throttled my laptop to the point that it was almost unusable you can change the attribute to _attribute but leave the power plan setting disabled.

447235c7-6a8d-4cc0-8e24-9eaf70b96e2b
Sets the processor power state when parked, I think the default is ok

5d76a2ca-e8c0-402f-a133-2158492d58ad
Option to Disable processor idle states, not really relevant on a laptop

a55612aa-f624-42c6-a443-7397d064c04f
Processor core parking override, this one is key, it you don't disable this in your power plan settings you will only park "virtual" cores

ea062031-0e34-4ff1-9b6d-eb1059334028
Maximum number of unparked cores, this is useful to put your computer into "dual core mode" in power saver if you set this to 25% or 50%




Thanks to eblock12 for the links:
Masaki Iwata's blog : Windows 7 ? Core Parking ??????? (japanese)

 

other the minimum brightness and disabling some processes in the background I dont see the battery life getting any better.

 

Are you using the 9-cell battery?

 

Yes, the i7 only comes w/ the 9 cell. How much battery life does a comparable C2D sXPS 1640 get? I think I read it was like 3.5-4hrs, which isn't much different.

 

It doesn't only come with the 9-cell. Over here it comes standard with the 6-cell (NL). Maybe only in the US it is default?

 

Oh my bad, in North America, we only have the 9-cell available. But yes, with those numbers, I would assume it was on a 9-cell.

 

Yes the i7 supports "core parking" which enables individual cores to be completely powered down. This requires support from the OS, and you need Windows 7 for it to work but it will happen automatically. If you load up "Resource Monitor" on windows 7 it will indicate which cores are currently parked.

In advanced power settings you can set what the maximum percentage of CPU throttling is, by default it will always go to 100%, so you lower it to force CPU throttling.

Also take a look at the "powercfg" tool: http://www.nullsession.com/2009/11/24/powercfg-unleashed/
There is a new parameter in Windows7 that not many people know about "powercfg -energy" it will automatically analyze the system and produce a report identifying issues that may prevent the system from saving power.

 

The 1640 comes with the 6 cell standard, the i7 powered 1645 only comes with a 9cell battery.

Thanks, eblock12, that's the sort of info that I'm interested in learning more about. It would be nice if you could force a core park? If you lower cpu %, is it just clock rate or does it actually park two cores if you set the max at say 50%?

 

My 1645 seems to only park the hyperthreaded cores. (every second core). It would be nice to force 50% to park.

 

I dunno, sometimes I see it park different ones. Such as right now, cpu 1, 2, 5, 7 are parked.

I found this blog post: http://blogs.msdn.com/masaki/archive/2009/10/01/how-to-enable-core-parking-on-windows-7.aspx

It seems to describe registry keys that enable core parking override settings, but unfortunately it's in Japanese.

 

Okay I took a chance and made the registry changes on the page. It does enable a bunch of new processor settings. You can force it to park the cores on battery, but I still can't get it to park more than 50%. Whats interesting though is you can turn on "Allow Throttle States", and the CPUs are throttled down severly, multiplier is set to 1x (133 mhz). The system is pretty laggy in this state but it does throttle up as load increases. I imagine you'd see some power savings with this.

Edit: If you disable "core parking override" it allows all the cores to be parked except one. Here I was able to get it park cpu 1-7.

 

Could you do some screen shots of the registry changes?
Any change in projected battery life?

Ok, I watch resource monitor and it will park different cores (it's sometimes jumps around a bit). But I have never seen it park more than 50% of the 8 logical cores.

EDIT: Ok I got brave, and changed "attributes" to "_attributes"
after a bit of messing around I've got it locked down to 2 physical cores at idle. I'd like to try this with a watt meter and see if I'm saving any wattage.

 

yea i would also would like a screen shot of the registry changes, i am afraid of messing up and than have to install everything from the begining

 

I have been thinking, i am planning on traveling and was going to use my laptop to watch movies, if i cut the processor to 2 for example it should cut down the power use correct? Is there any easy way to measure this?

I was think of cutting the processors but going to msconfig, boot, advanced options, and max processores

 

Is it ok for a 6-cell battery to last only 45mins on full brightness?

 

45min sounds minimal, considering I get substantially over 3 hours of light use with the 9cell. I wonder if the 6 cell doesn't have the grunt needed for the i7. Batteries usually have more watt hours of capacity at slower discharge rates. The faster you discharge a battery the less power it will give you.

 

because my system comes with 6-cell only, 45mins. remaining when fully charged and internet browsing only

 

updated first post with some new information.
link to first page

 

45 mins seems low to me if you're just doing basic web browsing.

 

45min is way to low. But the 6 cell may not be capable of adequetly powering the i7. When you overwork a battery it's performance goes way down.

 

It would be nice to get some battery runtime comparisions and and wattage comparisions with some of the registry edits.

 

I dunno if there's a windows equivalent of the app, but I just installed Ubunti 9.10, and it has a built-in nice battery life/history gadget. You can download and burn the ISO, and just boot off the LiveCD, and I'm fairly sure it should work.

You basically right click on the battery symbol on the top bar, select histry, and you get the app. Tells rates (charge and discharge) over time, charge amount over time. Also, std left-click on the battery icon and clicking the battery, gives battery info, like design power capacity, actual power capacity, wh on last charge, current wh left, time to empty (and time to full when charging) etc...

No, I'm not a linux pusher - I just don't know if there's a win equivalent, and I've happened to be playing with it the last few days to see what kind of life my lappie gets out of the two batteries I have (about 3H average, in case you're curious - 2/5 brightness, WiFi on, dual SATA HDD's running)

T