USB power-off on standby?

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csimon
Posts: 38
Joined: Wed Feb 13, 2013 3:07 pm

USB power-off on standby?

Post by csimon »

Is there a way to configure some USB ports to power off when the PC goes to sleep?

The background to this is that I want to power off USB DACs etc when the computer is not on but keep other ports active such as a USB keyboard and remote control dongle.

mbirger

Re: USB power-off on standby?

Post by mbirger »

USB ports on Intense PC behaves as follows:
USB ports on front panel (when using default FM-4USB FACE module) operational always, even at S5 (SW off).
USB ports on back panel (native) operational only during S0 active state, and off during all other Sx states (sleep, hibernate, off).

IntensePC_User
Posts: 44
Joined: Mon Feb 25, 2013 11:32 pm

Re: USB power-off on standby?

Post by IntensePC_User »

Hello mbirger. We're running Windows 7 on our Intense PC Pros.

In testing our units, the rear USB ports only turn off when the machine is actually off (S5) or in hibernation (S4). Sleep doesn't seem to disable these ports, though i'm not sure what version of sleep Windows uses (S1,2,or 3).

This operation seems to contradict your post. Is it correct operation?

Thank you.

csimon
Posts: 38
Joined: Wed Feb 13, 2013 3:07 pm

Re: USB power-off on standby?

Post by csimon »

I think I've found this as well. Wireless keyboard dongles remain active, and a device that just needs USB for power also remains on. However, a Xonar U7 USB sound card does power off. This must be due to USB signalling rather than the power actually being removed. I do have the settings in Windows that the computer can turn the sockets off to save power, but I don't know if there is anything else I should be setting.

csimon
Posts: 38
Joined: Wed Feb 13, 2013 3:07 pm

Re: USB power-off on standby?

Post by csimon »

Can soemone clairfy this again for me please? This recent thread http://www.fit-pc.com/forum/viewtopic.php?f=101&t=5822 suggests that the back plate USB ports are actually on during sleep S3. Could you clarify what is the intended behaviour of the USB ports during sleep in Windows 7 and, if they are suposed to be on by default, can we go back to my original question as to whether it can be confiugured to be off instead.

mbirger

Re: USB power-off on standby?

Post by mbirger »

Intense PC USB port power behavior:
http://fit-pc.com/wiki/index.php/FAQ:In ... r_behavior

1. FACE Module ports – USB power always on (S0, S3, S4, S5).
2. Motherboard back panel ports – USB power on in S0, S3 but off in S4, S5.

S0 – active
S3 – sleep
S4 – hibernate
S5 – shutdown

You can think of many different scenarios of smart power management where you would like to keep a peripheral device active (or not in sleep) while the host PC is in sleep to save power. There is no way to change this behavior, as it is by design.

csimon
Posts: 38
Joined: Wed Feb 13, 2013 3:07 pm

Re: USB power-off on standby?

Post by csimon »

OK, thank you, but I note the Wiki page wa sonly updated to mention this a few months after my original question, and contradicts the answer I got at the time.

I appreciate that there can be situations where you want USB power to remain on in sleep, but that's what the front USB ports do. It would have been nice to have the choice on the back USB ports rather than make all USB pros the same. There are many situations too where it is desirable not to have the power on in sleep but actually all 8 ports are provided without the option. A flaw in design I would say, and possibly an fault too if everyone thought initially that this wasn't how it worked.

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