Intel Core Duo USB Issue: A Mischaracterized Bug
by Anand Lal Shimpi on February 13, 2006 1:40 PM EST- Posted in
- Laptops
The Fix
The Microsoft Knowledge Base article that references the USB power drain problem also provides a solution to the problem, a simple registry edit that prevents the USB devices from keeping the processor from moving to lower power states. The entire text of the KB article was actually anonymously posted in a Slashdot thread, and thus, is now publicly available. As with any changes to your Windows Registry, be sure to hang onto a backup copy and make any modifications at your own risk:
The Microsoft Knowledge Base article that references the USB power drain problem also provides a solution to the problem, a simple registry edit that prevents the USB devices from keeping the processor from moving to lower power states. The entire text of the KB article was actually anonymously posted in a Slashdot thread, and thus, is now publicly available. As with any changes to your Windows Registry, be sure to hang onto a backup copy and make any modifications at your own risk:
A Windows XP SP2-based portable computer uses its battery power more quickly than you expect when a USB 2.0 device is connectedUnfortunately, the solution isn't completely ready for public deployment, as there are apparently still some scenarios where it doesn't fix the problem. There may be issues with the problem re-appearing after putting your system to sleep, which are presently being worked on. However, for the majority of situations, this simple registry modification should, in theory, take care of things. With the solution in hand, and five notebooks to play with, we went to work.
View products that this article applies to.
Partner Only Article Article ID : 899179
Last Review : July 12, 2005
Revision : 1.0
Important: This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 (https://premier.microsoft.com/kb/256986/) Description of the Microsoft Windows registry
SYMPTOMS
Consider the following scenario. You install Microsoft Windows XP Service Pack 2 (SP2) on a portable computer. Then, you connect a USB 2.0 device to the computer. In this scenario, the computer uses its battery power more quickly than you expect.
CAUSE
Windows XP SP2 installs a USB 2.0 driver that initializes any connected USB device. However, the USB 2.0 driver leaves the asynchronous scheduler component continuously running. This problem causes continuous instances of memory access that prevent the computer from entering the deeper Advanced Configuration and Power Interface (ACPI) processor idle sleep states. These processor idle sleep states are also known as C states. For example, these include the C3 and C4 states. These sleep states are designed, in part, to save battery power. If an otherwise idle portable computer cannot enter or maintain the processor idle sleep states, the computer uses its battery power more quickly than you expect.
RESOLUTION
Warning: Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk. To resolve this problem, add the EnIdleEndpointSupport entry to the USB registry key. To do this, follow these steps:STATUS
- Click Start, click Run, type regedit, and then click OK.
- Locate, and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\USB
Note: If the USB subkey does not exist, create it. To do this, follow these steps:
a. Select the Services key. On the Edit menu, point to New, and then click Key.
b. Type USB in the New Key #1 box to name the new key "USB."- Right-click USB, point to New, and then click DWORD Value.
- In the New Value #1 box that appears, type EnIdleEndpointSupport, and then press ENTER.
- Right-click EnIdleEndpointSupport, and then click Modify.
- In the Value data box, type 1, leave the Hexadecimal option selected, and then click OK.
- Quit Registry Editor.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
APPLIES TO
Microsoft Windows XP Service Pack 2, when used with:
- Microsoft Windows XP Professional
- Microsoft Windows XP Home Edition
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61 Comments
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mayurgala - Thursday, June 22, 2006 - link
Hi,as we saw tht MS has come with a registry fix which gets off once the machine comes out of the standby mode.... SO y cant we use hibernate it will just consume some more hard drive space :)
Hibernation vs Standby Mode are very similar and people tend to confuse the differences. Standby basically turns off power consuming components like the hard disks and monitor. It switches the computer to a low power state. Its much like a warm boot. Any contents of memory and unsaved desktop settings are lost. Hibernation saves state information by writing a hibernation file which contains the contents of memory and is thus the same size as total RAM. This is a snapshot of active memory. When you turn your PC back on, the state, including which applications are running (desktop) and the memory contents are restored to RAM and voila! - you are back to where you were when Hibernation mode started. The restoration of state can take place in 5 minutes, 5 hours, 5 days, 5 weeks, ....
Hibernation is only available if your system is ACPI-compatible. If it is not, the Hibernation tab will be missing and you will have an APM tab instead. To enable Hibernation mode as one of your Shutdown options:
V00D00 - Thursday, February 16, 2006 - link
The link to the microsoft kb article is bad, it takes you here:file://localhost/kb/256986
It's supposed to be:
https://premier.microsoft.com/kb/256986/">https://premier.microsoft.com/kb/256986/
IntelUser2000 - Wednesday, February 15, 2006 - link
Tomshardware: http://www.tgdaily.com/2006/02/14/microsoft_to_rel...">http://www.tgdaily.com/2006/02/14/micro...e_patch_...Anandtech: http://www.anandtech.com/mobile/showdoc.aspx?i=269...">http://www.anandtech.com/mobile/showdoc.aspx?i=269...
Can anyone tell me why both systems with EXACTLY the same configuration AND drivers behave differently in terms of USB 2.0 power drain problem??
If Anandtech is right about the fact that since Asus W5A/W5F has integrated USB 2.0 camera, connecting a external USB 2.0 device shouldn't affect battery life since it already has USB 2.0 device via camera installed.
However, it does not. While Anandtech's results are consistent with THEIR own conclusions that disabling the device doesn't remove the problem, the only way is to physically remove it, it doesn't show for Tomshardware results.
Summarizing the differences:
Tomshardware
1. With no external devices connected, Core Duo laptop has SIGNIFICANT battery life advantage over Pentium M
2. Core Duo laptop loses significant battery life when external USB 2.0 device is connected
3. Battery life AFTER the LOSS is STILL pretty much equal to Pentium M laptop
4. Pentium M laptop loses very insignificant amount of battery life with USB 2.0 device connected
5. Core Duo laptop AFTER THE PATCH GAINS significant battery life close to the result with no external devices connected, now the difference between CONNECTED and UNCONNECTED is within expectations
6. Pentium M laptop ALSO gains battery life after the patch, but much less significant then Core Duo laptop
Anandtech
1. Core Duo laptop has very little battery life advantage over Pentium M
2. Core Duo laptop loses insignificant battery life when USB 2.0 device is connected
3. Battery life after the loss is pretty much equal to Pentium M
4. Pentium M laptop loses insignificant battery life with external USB 2.0 device connected
5. Core Duo laptop AFTER THE PATCH gains significant amount of battery life
6. Pentium M laptop ALSO gains SIGNIFICANT amount of battery life.
Anand??? Tom??? Who the hell is wrong here?? Will you two sites stop bashing each other who has more "professional" journalism and cooperate, see what's wrong?? So umm, MAYBE WE KNOW WHY THERE IS A DIFFERENCE??!!
clnee55 - Wednesday, February 15, 2006 - link
Don't know who is right and who is wrong but at least THG is more consistent. Anand's conclusions are contradictary. Ex: 2 and 5. If the CoreDuo loses insignificant when USB2 is connected, how can it gain significant after the patch. Same contradiction between 4 and 61. Core Duo laptop has very little battery life advantage over Pentium M
2. Core Duo laptop loses insignificant battery life when USB 2.0 device is connected
3. Battery life after the loss is pretty much equal to Pentium M
4. Pentium M laptop loses insignificant battery life with external USB 2.0 device connected
5. Core Duo laptop AFTER THE PATCH gains significant amount of battery life
6. Pentium M laptop ALSO gains SIGNIFICANT amount of battery life
NullSubroutine - Wednesday, February 15, 2006 - link
i dont think his summary was accurate to what anand what saying. which was under all circumstances usb 2.0 makes Pentium M and Core Duo lose battery power due to the issue with windows.thg diabled the camera THOUGH the bios, where as i believe anand did it inside windows.
tyildirim - Wednesday, February 15, 2006 - link
And what about how swap cd/dvd bays alot of IBM's dell's has (also my d600) a removable internal cd writer in the task bar is si seems to be an usb device added to the system which I can "safelym remove" etc. so will it also affects battery life? quite confused now?hardcandy2 - Wednesday, February 15, 2006 - link
A similiar thing happens to the Dell Axim x50v with WM 2005, a battery drain takes place, due to a "file manager"(?) that keeps running. Saw it posted on www.aximsite.com a while back. Going by memory here which is not the best this AM.paulsiu - Wednesday, February 15, 2006 - link
Ok, the driver architecture is likely to be different, but does the problem occur under Linux?NullSubroutine - Wednesday, February 15, 2006 - link
i just read toms update, anand is by far better written, more informative, and used better methodoligy. go anand!mark1 - Tuesday, February 14, 2006 - link
Mark Twain had a saying, pardon my paraphrase, that a lie makes it halfway around the world before the truth gets its shoes on.THG has zero credibility. Their smug little article is still up and my bet is will stay up uncorrected so all the AMD fanboys can chortle about mighty Intel stumbling.
Turns out, THG tried a little too hard this time. So they found 'dirt'; turns out the same phenomenon afflicts all Sonoma product, too.
Before you know it, the story will have morphed into: plug any USB into a core duo and it drains the battery instantly. Heck, I was just at a retail store last weekend and was warned by a "salesman" that Duos have a battery drain problem. I asked him if he reads Tom's Hardware a lot - he wasn't ready for that. Or for that fact that I said it is a USB implementation, really nothing to do with the Centrino product. But the next 50 customers will get the same 1/2 truth. And all 1/2 truths are is lies.