Intense Power Savings

In my (near obsessive) desire to get absolute maximum battery life out of my laptop, I have decided to see what the collective suggests. All anecdotal and empirical evidence is welcome.
The key is to get the best possible battery life without totally crippling the user experience.

So far I have disabled all rarely-used hardware, adjusted all power-plans to their most stringent levels I can find. The more obscure options are troubling however.

In Vista, the hard drive seems to be accessed a lot, even when I manually disable the Indexing service. It appears Firefox is writing/reading cache files preventing the hard-drive going into a sleep state.

I have read that due to this, it may be better to set a longer sleep-delay to prevent the HDD spinning up and down constantly hence using more power.

How about forcing the kernal to run in RAM?

What are the optimum power savings for the Intel Wireless?

I even read that choosing 16bit colour depth saved some power!

How about Aero Glass vs Aero Basic vs Classic... does anybody have data on these... does Aero Basic still use the GPU to render?

Undervolting on Santa Rosa has not yet been perfected so there is scope there also...

 

I want to see the answers to this too...

 

Make sure you installed FlashBlock for Firefox. Flash on web pages and keep the CPU active if you have Firefox open even if you are off-line.

I also found on my Samsung Q35 that Bluetooth stopped the CPU going into the C3 low power state.

As for the HDD activity problem, this is where Turbo Memory or a hybrid HDD should help. When Anandtech re-looked at Turbo Memory they concluded that it reduced HDD activity.

John

 

Sure, can't hurt. I always do that anyway. It probably won't have an effect here though (since the kernel will only get paged out to the hd when you're low on free ram, and the system is busy)

I doubt 16-bit colors will make a difference, but that depends entirely on the GPU. Try it, I guess...

 

I use adblock in Firefox to block flash. I have turned off Bluetooth and virtually every other non-critical hardware item (other than wireless lan).

I tried to get clockgen to run, but I don't know how to set it up since I can't identify the clock generator in my machine.

Any thoughts on whether it would be better to have the HDD spin down faster or slower based on Vista's usage of it.

Unfortunately, most of us don't currently have Turbo Memory or a Hybrid HDD so it is all about maximising what we DO have!

 

I also wondered if it would be more efficient to run pictures, music etc from a USB key rather than the HDD?

Would turning off the browser cache reduce disk access?
How about turning off IM conversation logging?

 

I found that with Vista on my Q35 I could get a significant increase in DVD playing time by using an SD card for ReadyBoost. Vista then read the DVD intermittently and (I deduce) used the SD card as cache.

Can you do a %C3 time plot in perfmon? What voltage range does CPU-Z show for your T7100 (my T7300 is showing 1.0V at minimum speed (1.2GHz). Also using the latest RMclock beta, use the battery details tab to monitor the power drain when running on battery (you must be getting around 10000mW (=10W)).

John

 

Maybe try doing some Firefox tweaks, a lot of things can be done in About:Config. Try this guide, they list them all so maybe you can try making Firefox keep more stuff in your ram.

I also think Turbo Memory is the next best thing, it only costs 20 something dollars and its been shown to help on battery life during idle.

 

RMClock has my Min/Startup as 6.0x1.00V, but current as 8.0x0.900V... I have never encountered this before but assume it must be something to do with the Santa Rosa platform. I am apprehensive to undervolt without understanding it fully, so that will remain a later project.

How does checking "Ehanced Deep Sleep States" effect things.... I know the theory but does it work? If so, why aren't these settings defaulted to!

I will do the perfmon test in a bit.

 

In RMClock, what does "Enable Slow-C4 Exit" option do?
Does this increase or decrease power usage?

 

Intel does some interesting things with the SR platform. the 6x @ 1.0V is what I am seeing. I think the 8x @0.9V is actually 800MHz @ 0.9V with the FSB speed halved. I have not see this effect on my notebook and I suspect it is one contribution towards your good battery time.

I think this is to do with the CPU whine problem which affects some notebooks. Leave it at the default.

John

 

The C3% seems to be hovering between 80-90%.

 

I can also confirm the Q45 doesn't enter the C3 state while on AC power, I know some people had wondered about that.

 

Using BatteryMon to monitor the battery discharge since MobileMeter doesn't run in Vista (as far as I know). I accidentally set the polling rate to once every 30s so I can't make a decent plot at the moment. I will look at the log once discharged and attempt to construct a graph and some figures.

Here are the the discharge rates in mW over a 10minute period:

9324, 10556, 10501, 9513, 14519, 11633, 9768, 10212, 9801, 13098, 14663, 12055, 10478, 9746, 10012, 10168, 10501, 9313, 10934, 11500

 

Interesting that I gained 4hrs 53mins on this run, with the following setup:

Hardware Disabled (Optical Drive, PCMCIA Slot, Bluetooth, Firewire, LAN, Modem, Card Reader)
Windows Classic Mode, 16Bit Colour, Maximum Performance Options
Indexing service stopped
Disk Defragmented
35 running processes (including MSN Messenger, Firefox, BatteryMon, RM Clock)
Page File set to 0
All power saving options enabled on Hard Drive using Hitachi Feature Tool
Wireless Adapter set at all maximum power saving settings
RM Clock used to enable deeper CPU sleep states

 

For all the trouble, just get a spare battery.

 

It isn't about the battery, just about personal satisfaction knowing you have tuned to the max.

 

Thanks for the updates.

If batterymon is writing to the HDD then it could be causing increased HDD activity and reducing your run time.

It would also be interesting to know whether RMclock is making a difference to the power management under low load conditions. I've got C3 and C4 enabled on my Zepto but the CPU never goes into those states, with or without RMclock. You should find that the Q45 goes into C3 on battery irrespective of RMclock running. Personally, I would also like to have C3 enabled when running on mains since it should help cool and quiet operation, but it is probably disabled in order to give slightly better performance.

As for the spare battery, Samsung's pricing of batteries is exhorbitant, but I bought a spare for the Zepto I am using (1/3rd of the cost of a Samsung spare battery).

John

 

From my analysis, running RMclock doesn't effect the C3 state. I did read however, that Perfmon won't show the C4 state discretely, and instead represents it as the C3 state on the graph... so I may have been in C3 OR C4.

My next two ideas are:
1) Disable one core in the BIOS
2) Enable Thermal Throttling in RMclock (Reduces CPU throttle to around 360Mhz, though Core Clock remains the same)

I have read conflicting reports about these two things so I will know for sure when I try them out.

I did consider that there was additional writing to the HDD so I will try it without that next time. I am also surprised to see removing the pagefile from the HDD seemed to make no difference at all, as did being in Windows Classic mode versus Aero Basic.

 

Did you try reading the relevant data sheet for the CPU.

Section 2 (Low Power Features) and Section 3 (Electrical Specs) are interesting although the latter gives very broad ranges. For example, it seems that my T7300 is preset to to 6x (1.2GHz) @ 1.0V and 10x (2GHz) @ 1.25V. However, I've pushed the latter down to 1.05V without ill-effect but I can't get sight of the low voltage 800MHz mode.

Enjoy!

John

 

I just hope RMclock's creator gets his head around it...

 

It turns out the T7100 has 4 FIDs (6.0, 7.0, 8.0. 9.0). On my CPU, all are stable at 1.000V but RMclock gives me no lower FID options.

Now I am not sure which is the best way to run Vista & RMclock... should I let RMclock take care of power management (and possibly risk losing the 800Mhz mode!) or just use it to undervolt and let Vista handle things.

In my ORTHOS stress test, maximum temperature decreased from 68C to 56C @ 1.8Ghz (9.0x800Mhz)

 

That's kind of odd. The T7300 in my Asus W7S goes to 800MHz @ 0.9V just fine, in fact it's there most of the time. Have you got the minimum CPU power state to 0% in Power Options? (It's under the advanced settings, you have to kind of dig to find it.) This is with Vista's default power management options too...I uninstalled the pre-installed Asus power utility because it was just kind of annoying to deal with.

 

It goes to 800Mhz fine when RMclock isn't running, but when it is running 1.2Ghz is the minimum.

 

5hrs 3mins
Pagefile in RAM
Aero Basic
NO RMClock

==
It seems to me the key to missing run-time is if RMclock could enable the 800Mhz mode since it can then enable the C3 and C4 states.
Unfortunately at the moment RMclock offsets this advantage by making the CPU run at 1.2Ghz @ 1.000V

 

try pushing your voltage even lower (Y) if anyone can do it i am sure it would be you and force your CPU to run at 30 % i am sure you will have more then enough processing power for typical use and lower your screen brightness >.<

you should put your voltage arround .97 Volts untill you hit the 11th the 12th and up can be stable at 1.06v

 

RMclock only allows minimum voltage of 1.000V at all multipliers.
The T7100 only has 6, 7, 8, 9x multipliers (x200Mhz)...

Reducing CPU speed to 30% (throttled) didn't seem to make any difference to power usage, which was quite disappointing

 

How come only 1.000V? I thought the lowest on RMclock was about 0.937V on all multipliers for C2D (on mine it is). Maybe you could try pressing 'default' and then 'apply' and see if you can change the volts lower afterwards?

I must agree that an idle C2D without RMclock running at 800MHz 0.850V is better than 1.2GHz 0.937V with RMclock.

 

No, definitely 1.000V is the minimum. Is your C2D the Santa Rosa refresh?

 

I'm not sure what a 'Santa Rosa refresh' is but from what I gather it appears to be a bog standard C2D Merom, here's a pic of my settings with the 0.937V

 

You are lucky. My T7300 is set to 1.0V minimum voltage. It looks like Intel are not only setting each CPU with a voltage for the maximum multiplier (my T7300 was set to 1.25V) but also presetting minimum voltage values within a range. There is also an even lower voltage for the 800MHz setting (this halves the speed of the FSB so it may be reported as 1600MHz). See the attached example which shows 0.85V (that's for the Samsung Q70 I reviewed. I'm waiting for Zepto to give me a BIOS which enables this function - they know it isn't there at the moment).

John

 

Am i right in thinking that the newer C2D Merom would have a locked minimum of 1.000V?

I mean my T7500 can throttle down to 800MHz @ 0.850V as well but I just wasn't aware of the 1.000V limit that some people are having with Santa Rosa

 

The T7500 CPU is indicative of the Santa Rosa chipset, and if you are getting less than 1.0V then it indicates that not all the SR-compatible CPUs are locked at 1.0V minimum (aside from the 800MHz mode which should have a lower voltage). I also presume you are referring to the CPU in your W7S. If Intel is producing the same CPU with a range of minimal voltage settings then it does confuse the business of estimating and comparing battery life.

John

 

0.850 would be tasty indeed!

 

Uh, rather than doing all this maximum power saving stuff why don't you buy a spare battery? It would be much more effective than saving the half hour or so you will save doing all this stuff.

 

Because a) spare batteries can cost £100+ here ($200)
b) spare batteries take up room and increase weight
c) for the fun of it

I don't *need* the extra time it provides, I just find it interesting.

I am sure the 99.999% of computer users who don't know about this forum would think we are all wasting our time.

 

Back on topic, I had been discussing disabling one core of the Core2Duo in the BIOS but I had read this actually decreased battery life time since one core working harder was inferior to two cores sharing that task.

My own initial evidence (15mins worth) is that it DOES result in a power saving. I have nothing to hang my hat on yet, but my power draw is now occasionally dropping below 8W, wheras before it would be stuck at 9.

 

Here is the data I recorded over a 1hr period. Vertical axis is mW, horizontal is minutes.
I am not sure why my initial testing seemed to indicate single core was better, but here is the proof that dual core operation does result in lower power use.

Conditions of test:
Windows Classic Theme
Best Performance (except smooth screen fonts)
Indexing Off
800Mhz CPU
No Pagefile
Using Firefox & MSN Messenger

 

Interesting graph. Do I read that the average dual core power is lower?

How did you log the power consumption and create the graph? At the moment I'm struggling to get my Zepto below 20W!

John

 

I used batterymon to create a logfile (you can adjust the polling period - I chose 1min) and then put those figures into excel (I had to do it manually, couldn't figure out how to import the data from the .txt file). It was a pain in the arse using Excel 2007, it seems impossible to do a time-based graph with ease so I had to fudge it by using "time" on the horizontal axis.

The figures are unusual I agree since as I mentioned earlier, idle usage was 9W - but then I changed to Windows Classic theme from Aero Basic. I had heard there was no difference between those two but the results speak for themselves. I also made a plot of projected lifetime that came to 5hrs45mins but that seems inaccurate to me so I might repeat the tests later on today.

If anybody is curious, the reason I have so much time to do these stupid things is that I am in my university holidays until October.

 

If you want to rotate so your horizontal axis is vertical, Highlight data, Copy | Paste Special | select transpose | OK

 

It's time to resurrect this thread and point out that RMClock 2.35 beta 1 is now available. It includes Santa Rosa support . The most interesting feature is that the voltage range down to the SLFM voltage appears to be accessible for all the speed range.

John

 

John...can u tell me more about RMclock ....from what i perceive it runs processor on lower voltage?

 

You perceive correctly although the overall voltage range is hard-coded into the CPU. Most Core / Core Duo CPUs (and the Pentium M series) will run at lower voltages than pre-set by Intel. Lower voltage = less heat. There's more here and here. The next version of RMClock with Santa Rosa support is now being beta tested.

John

 

I just started using RMClock 2.35 (2/29/08 release) and this may be obvious to you guys, but in case it isn't, I found that the 0.85 voltage on my T7500 CPU became visible in RMClock when I changed one of the default settings under "Advanced CPU Settings" CPU type. In that screen the default is set to "desktop" and with that setting the lowest voltage available for my CPU was .925. When I ticked the "mobile" box, the available voltages dropped to .85.

Also, I couldn't get the lowest 800 mhz speed to work while in RMClock initially until I checked the 0 box box under the performance on demand profile. Now everything seems to be working quite well with RMClock, and I'm working my way down to lower and lower voltages, so far without any problems.

I'm not sure if I did the right thing in enabling all the various C3, C4 etc. enhanced deep sleep modes, but so far it seems to be still working OK.

I wish I understood this program better, but I think I'm figuring out how to get some benefits out of it.

 

well there are several things that you can do to increase your laptop runtime. Personally i set the graphics to 16bit (it does help), i also lower my screen brightness via the intel graphics utility. I play starcraft alot, but since the optical drive does take up alot of power (even when it is not in use) i use a program called magicdisc to create a virtual cd drive on the hard drive where i can run my games on. I also use an n-lited version of xp and disable alot of the services at start up. Lastly turn off any unnecessary ports for me i disable 1 usb port and the expresscard port. If your on vista your doomed but try readyboost, i'm on xp and use eboostr with a superfast mmc card (200x).