Power Issue (I think)

[Dougal 165]

I don’t recall when this started, but if the power supply in my PC is switched on at the mains, then even before booting the PC, all the motherboard and case LEDs are on.  Also, if the PC is completely powered down at the mains, once applying power from the PSU, all LEDs light up, PLUS there’s a small noise from the DVD player, so that’s also receiving power from the PSU prior to booting.

I removed the PSU and tested with another (smaller) unit, and the issue stopped.  As a result of this, I purchased another new PSU, assuming this one must be faulty. Not so it seems as, having spent almost £100 on the new PSU, it also happens with this one too.

I know it’s not a motherboard issue, as that’s been replaced under warrantee, after another separate fault.

Also, if the PC is powered down, even unplugged, then the motherboard and PC case LEDs also remain permanently lit, until removing the USB powered hub. This means power is going back INTO the motherboard from the hub.

Is any of this normal?

[martin-w 3,234]

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I don’t recall when this started, but if the power supply in my PC is switched on at the mains, then even before booting the PC, all the motherboard and case LEDs are on. 

 

Normal behaviour Dougal.

My daughters PC is off at the moment, but the switch is on at the wall.... lots of nice RGB led's glowing courtesy of the Strix motherboard. PC's always do that.

 

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, if the PC is completely powered down at the mains, once applying power from the PSU, all LEDs light up, PLUS there’s a small noise from the DVD player, so that’s also receiving power from the PSU prior to booting.

 

Normal.

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I know it’s not a motherboard issue, as that’s been replaced under warrantee, after another separate fault.

 

You have no issues. Don't worry.

 

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Also, if the PC is powered down, even unplugged, then the motherboard and PC case LEDs also remain permanently lit, until removing the USB powered hub. This means power is going back INTO the motherboard from the hub.

 

I don't have a powered USB hub, but that sounds normal to me too.

Don't worry.

[LRW 42]

I would not use a hub that is backfeeding that much current into my mobo.  Current should not go in directions or places that it's not supposed to.  While I don't think it's uncommon for powered hubs to backfeed some current, it's a result of cheap manufacturing.

[Dougal 165]

7 hours ago, LRW said:

I would not use a hub that is backfeeding that much current into my mobo.  Current should not go in directions or places that it's not supposed to.  While I don't think it's uncommon for powered hubs to backfeed some current, it's a result of cheap manufacturing.

I'm sure you're right.  I'm not at all happy with this happening.  Power is even being supplied to one of the m/b fan headers, meaning at power down, not only are ALL the LEDs illuminated, but also the two front case fans are spinning at low rpm.

I no doubt bought the hub from eBay, so I shouldn't be too surprised.

If anyone can recommend a powered hub that's tried and tested NOT to do this, I'd appreciate it.

thanks

[martin-w 3,234]

I've seen this reported a number of times when I googled yesterday, so not uncommon. I do think that before definitively stating it's in some way bad and worrying about it, we should find out whether it is actually undesirable or not. Facts are always best.

Not saying it's not, as I've not had any experience of powered hubs, but it could well be that it's not any kind of an issue at all.

[LRW 42]

You're right, Martin.  It might not cause any problems at all.  But I tend to be conservative with things like that, especially if they're sending enough current to power up fans.  I disconnected my powered hub about a week ago because I was having intermittent issues with the devices plugged into it.  I don't know if it was the same problem or not, but I don't want a $30 hub potentially frying my $200 mobo or $150 PSU if it goes completely nuts.

[Dougal 165]

I would like to hope that if it was truly bad for a PC, then M/B manufacturers might put diodes in place to stop it. Very annoying though, as is the PSU never shutting off all power and allowing fans to spin:-(  Especially in the warmer months, as I remove the top and front panels. It does often supply a little light entertainment, as one or more of the dogs attempts to sniff the strange 'spiny things' ;-)