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Fingerprint scanner draws extra power?
Posted: Sun Aug 31, 2008 11:28 pm
by g2tl
I posted up on
gottabemobile's forum as well, but here we go.
For obvious reasons, of course the fingerprint sensor draws power :p
But what I may have discovered is a bit more than that.
I never had this problem until fairly recently, but it seems like installing the fingerprint software prevents the system (x61t) from going into idle state; wattage never goes below 10W.
I discovered this through bruteforce, installing and uninstalling, reboot after reboot, reformat after reformat.
Currently, I use Vista SP1 with all the updates except the fingerprint scanner.
Can anyone else confirm this using both/either 5.6 and/or 5.8? I use RMClock to measure the power drawer, and I stay around 8.5W half-idle, 8W idle. This means around 8 hours (of idleness) for my almost new 8-cell battery and a little less than 3 hours on my old 4-cell battery.
I also have noticed that using Mz Vista Force tweak app locks the lowest possible power consumption at 10W. I have not been able to test each option yet.
And last but not least, the 64-bit version of Vista gets me into this mess no matter what I do. I can't get the power consumption below 10W
I have the L7500 processor, 4GB RAM, and a Turbomemory card. Both superfetch and readyboost are enabled. But they didn't really contribute much regarding the power consumption at idle state. I'm sort of hoping the cache will come in handy when I actually launch programs on the go.
Posted: Mon Sep 01, 2008 5:09 pm
by awolfe63
My x61s has the fingerprint scanner active and I often get down to 8W.
Posted: Tue Sep 02, 2008 2:40 am
by lightweight
The fingerprint reader uses USB 1.1, which does draw power unless you disable it, but this wattage is trivial until you get past large wattage consumers. If you cannot drop below 10w on your x61t, look at more likely problems (#1 is probably screen brightness/backlight and/or CPU staying in the C1/C2 state). Perhaps it is impossible to get a touchscreen under 10w. Like awolfe, my x61s and x60s can drop below 10w with USB 1.1 disabled, but with LCD turned down, CPU stepped down, bluetooth disabled, power saving on the wireless card, etc.
Posted: Tue Sep 02, 2008 5:31 am
by artic_squirrel
how do you mesure the wattage ?
Posted: Tue Sep 02, 2008 4:29 pm
by Volker
I would also suspect the USB 1.1 running and preventing the CPU from reaching deeper sleep states. Here are some hints if you don't want to get rid of the whole USB 1.1 subsystem:
http://www.thinkwiki.org/wiki/How_to_en ... ng_too_hot
Posted: Wed Sep 03, 2008 11:10 am
by coldfire
x61t, L7500, SXGA+,4GB
I am using XP Tablet Edition, with wireless on and normal LCD brightness, the discharge rate never goes below 10W. The 4cell battery most time just give me less than 2 hours of use.
I've tried to disable fingerprint reader (uninstall driver), it did not make a huge difference.
I would be interested if you can talk a little bit about how you managed to get 8.5W rate.
Posted: Wed Sep 03, 2008 11:34 am
by aceo07
awolfe63 has a x61s, not the x61 tablet. That's probably how he gets 8w. I have x40 and I can usually stay under 8w with lowest brightness and wifi on.
I'd be curious to learn how to turn off the fp scanner too. Besides logging on, I don't see why the scanner should be powered on.
I'm hoping to receive my x61t before the end of this month. The tablet seems to like to drain power and I'd like to minimize it as much as possible.
Posted: Fri Sep 05, 2008 2:04 pm
by g2tl
lightweight // everything is at the lowest state possible. But if I install the fpscanner, it won't drop below 10W
artic_squirrel // I use RMClock (make sure you set it to "mobile" in option
Volker // but that's for linux

I tried a few linux distros, but none of them support the passive digitizer
coldfire // I used to have an xp partition, but got rid of it because I never used it. I liked the speed, but didn't like the lack of tablet features, including the lackluster handwriting recognition (this can become an issue for a constant onenote user)
I don't remember all the settings, but I think I installed the following, and the following only--all latest: intel chipset, lenovo interface, hotkey, matrix storage (not sure about this one), ibm power management (not power manager), x3100 driver, multitouch driver, tablet button+shortcut menu, active protection, and all those power saving patches (4 of them, I think). I don't think I even installed the audio driver.
On Vista, I installed the above, pretty much in that order except the turbo memory after the lenovo interface. Then I did windows update.
See if notebook hardware control or RMClock helps you.
aceo07 // I simply didn't install the fp scanner. I found it more of a hassle than a convenience, since I'm not too worried about security breach or anything. If password protection is ever a concern, try "lastpass" for firefox and ie
Posted: Fri Sep 05, 2008 3:02 pm
by aceo07
g2tl wrote:
...
See if notebook hardware control or RMClock helps you.
...
aceo07 // I simply didn't install the fp scanner. I found it more of a hassle than a convenience, since I'm not too worried about security breach or anything. If password protection is ever a concern, try "lastpass" for firefox and ie
NHC is just awesome. I have it on a couple of thinkpads and I dropped the voltages down lower than on ULV processors.
For the x61t, which I hope to have in my hand soon, I probably wouldn't do any real private work on it in public. The fingerprint reader is something cool that I'd just use for logging in.
Truecrypt is what I'm planning on using for data security/encryption. I can use portable versions of Firefox/OpenOffice/misc and lock it up in truecrypt partition along with private data.