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Old 07-08-2010, 06:47 AM   #3 (permalink)
mikeytunes@yahoo.com.sg
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Default USB power

I have 2 desktops (Acer, Dell) and 4 notebooks (Lenovo X200, Acer 3810, Dell D610 and Sony). After reading this I tried played with all of them and here are the results

1) All of them except for the Dell had power when the PC is in standby.
2) The Lenovo was a bit strange. It had power when the AC adapter was plugged in but not when it was disconnected. It also seems like the DOCK USB power runs from the PC so I cannot keep the dock plugged in and charge without the PC
3) Dell was an OLD system so it did not have the option of leaving USB power ON

After investigating some more and talking to a buddy who helps with PC design in Taiwan, here are some of the conclusions I came to (if incorrect please feel free to correct and I will recheck things with him)
1) Almost every desktop will have USB power available in standby IF it is turned on in the BIOS. There is an option to turn this off.
2) Different notebook makers approach things differently.
- Most of the top 5 notebooks sellers ACER, HP, LENOVO and APPLE all have power when the AC adapter is plugged in and PC is in standby(Dell below is the exception). But this power does NOT mean you can charge your devices with a regular USB cable because the USB chips are off.
- LENOVO does NOT have power when the adapter is not plugged in but does supply it when the adpater is in
- APPLE and ACER do have power when the PC is in standby even when AC adapter is present
- DELL does something completely different with something called POWERSHARE. I still cannot understand what this is but it looks like it is supposed to be able to charge any phone when the PC is off. But it does not do as advertised - FALSE ADVERTISING??....NO WAY!!!

My buddy also tells me that according to USB standards, they are supposed to have this standby power to enable wake on USB. But not all PC makers do this....

Hope this helps..

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