Why is my hardware switching on a smart power strip if the desktop is off?

I bought a smart power strip to manage my electricity usage at home. I have a large desktop machine that is my main computer during the times when I am at home. I have my main power supply hooked up to the master outlet on the smart power strip, and all other hardware (my speakers, monitors, and an XBox Kinect) hooked up to the slave outlets. When the master outlet is not being used, electricity should also be cut off from the other components.

When I turn off my desktop at night or when I leave for work, the other components shut off as expected. However, I have been noticing that when I come home or sometimes after I shut down my computer, the monitors and speakers will be on (indicated by the illuminated LEDs in the hardware).

I have been trying to figure out what the cause of the problem is, because this had not been happening when I initially bought the power strip. I have tried adjusting the sensitivity on the smart power strip, but this has not helped. Could this issue have been caused by my machine or is it a problem with the smart power strip itself?

UPDATE: I'm using a Smart Strip LCG5 manufactured by BITS Limited. A lot of people have been leaving negative reviews on Amazon for the LCG3 model because of a problem that sounds similar to mine. BITS Limited customer support has been leaving comments on those reviews, and I am currently corresponding with them to fix my problem.

Matt Chan

Posted 2013-04-12T14:46:13.623

Reputation: 511

Are the other devices also powered on or just the monitors? – Brad Patton – 2013-04-12T14:52:23.360

What operating system are you using exactly? Windows 8 has a hybrid shutdown which might explain the behavior. – Ramhound – 2013-04-12T15:01:16.357

2How do you "turn it off"? Power off, suspend, sleep? (You might try actually unplugging the computer after shutting down, to see if the problem persists when you do that, indicating a power strip problem.) – Daniel R Hicks – 2013-04-12T15:52:27.133

I'm doing a full shutdown in Windows 8 (I actually upgraded to that not too long ago) from the menu that slides in the right, settings, and then a full power off rather than sleep. Any devices plugged into the slave outlets are all powered on. – Matt Chan – 2013-04-12T16:01:11.320

The PSU will still draw power even if you turn the PC off. You can confirm this with an ammeter or Kill-a-watt device. A high-wattage PSU (>700W) might use 4 or more watts even though the PC is "off". – sawdust – 2013-04-12T18:41:05.050

@MattChan - So you have disabled hybrid shutdown? Its enabled by default. So if all you are doing is CTRL-I and then doing a Shutdown that would be a hybrid shutdown ( provided your hardware supports it ). – Ramhound – 2013-04-12T18:56:47.830

I don't believe you will need something as complicated or expensive as an ammeter or watt measuring device. Plug something into one of the USB ports and turn the computer off. If you still have power, then you are still drawing power. Quite common now to have desktop motherboards provide continuous power to some or all USB ports to charge phones, mp3 players, etc. – Bon Gart – 2013-04-12T20:17:02.377

@Ramhound I'll check when I get back home since I'm currently away for the weekend. I thought I had it disabled, but I don't believe my hardware supports it either. – Matt Chan – 2013-04-12T22:10:03.773

@BonGart - It's also not impossible for the USB ports to be turned off while the system is still drawing substantial power. – Daniel R Hicks – 2013-04-14T02:14:07.370

1Did you try unplugging the computer after you power it off? This would eliminate "vampire" power as the cause of your problem. – Daniel R Hicks – 2013-04-14T02:15:00.390

1@DanielRHicks I'm not sure I see where you are going with that. Older systems actually turn off and cease drawing power when they are set to do so. Systems that have Power On LAN enabled in the BIOS will draw power even after they are turned off. Systems that provide power through Always On USB ports will always draw power. Thus, if a system that continually draws some power is connected as the Master to a Smart Strip, the Smart Strip won't recognize the difference between what you consider to be off, and what is actually off. – Bon Gart – 2013-04-14T18:42:18.010

1I'm just saying that, by unplugging the system (and seeing if the power strip still "malfunctions"), you can perhaps determine if the problem is with the level sensing in the powerstrip, or an out-and-out malfunction of the strip. – Daniel R Hicks – 2013-04-14T23:45:06.100

I can confirm that in my Control Panel that fast startup is disabled. I did not see the effect last night, and nothing else has changed in terms of hardware or settings. I'm not sure why this is suddenly not happening after occurring for nearly a week. I might just chalk this one up to a bad smart power strip. – Matt Chan – 2013-04-16T04:39:38.393

The desktop is definitely drawing power. Turning it off or unplugging turns off the master switch and the speakers and monitors go out too. Their power is cut when the PSU's power is cut (is also indicated by a green LED on the smart power strip). Something is still causing the desktop to draw enough power to turn on the other hardware, but I still haven't figured it out yet. – Matt Chan – 2013-04-17T02:22:52.413

Answers

After following up with BITS Limited's customer support, here are the steps I took to resolve this issue.

I was told that the next time the problem arose that I should unplug all the computer from the "master" outlet and observe whether the peripherals turn off or not. Alternatively, toggling the switch on the power supply will also have to same effect as unplugging. This would rule out any possible issues that lie within the computer or peripheral hardware. After following these steps, my hardware specifically does not appear to be the problem.

My next step was to turn the dial on the smart power strip counter-clockwise as far as it could go after shutting down for the night. The computer and peripherals turned off as expected. However, the peripherals would not turn on once I powered the main CPU again. Adjusting the sensitivity dial (turning it clockwise) to a certain point would trigger the switched outlets and the monitors, speakers, and extra equipment then switched on.

Customer support followed up with me on this and proceeded with instructing me to follow these instructions:

Turn the computer off (completely, not on standby). Cycle the power switch on the power supply to ensure it is not remaining energized.
Turn the sensitivity dial on the smart power strip all the way counter-clockwise.
Turn the computer on. Peripherals may not come on (which was expected in my case).
Turn the sensitivity dial clockwise in very small increments. Wait 3-5 seconds before moving the dial clockwise again.
Repeat Step 4 until the smart power strip activates the "switched" outlets or until the dial reaches the end and can't turn anymore.
If the power strip activates before reaching the limit, then the peripherals come on. Turning off the computer at this point should turn off the other devices.

Following these instructions resolved my problem. I have not seen the problem I was having since I made the finely tuned adjustments so it may just have been an issue where I really needed to dial things carefully. There are two things that I can surmise from this:

Somehow my sensitivity dial got adjusted despite being in a hard-to-reach location
My power requirements were somehow adjusted though I would have expected to see this problem manifest earlier
Or maybe both were factors

Had the above instructions not resolved my problem, then BITS Limited would have replaced my smart power strip.

Matt Chan

Posted 2013-04-12T14:46:13.623

Reputation: 511

A modern PC is not truly off unless you unplug it or flip the switch on the power supply itself (typically in the back - OEM power supplies to this day still don't have this as a standard feature.) It consumes a small amount of power, necessary to support timed wakeup, wake-on-LAN, etc.

It does sound like your smart power strip's power sensitivity is not reliable.

Maybe try putting a device that has a physical on-off switch in the master socket, like an external hard drive or some other device that you won't have powered on without the computer also being powered on. You may have similar issues with using a monitor as that device as most of them aren't truly off unless unplugged either.

LawrenceC

Posted 2013-04-12T14:46:13.623

Reputation: 63 487