What would cause case fans to be powered by the HDMI cable in the GPU

Zepher

[H]ipster Replacement
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I was working on a client's PC earlier tonight. it's an older Z97 setup, Asrock Z97 Extreme with a G3xx something 2 core CPU, Corsair CX750 and an MSI 660Ti.
I powered down the PC and 2 of the 3 case fans were still spinning, bottom case fan, and the front fan which has LED's and they were still lit.
Unplugged the power cable and those 2 fans were still spinning and the front one still lit up. thought it might have been residual power but when I stopped the bottom fan with my finger, it started spinning again.
Unplugged the HDMI cable and they turned off. I thought that was really strange. Plugged the HDMI cable back in and they started spinning and lit up.
The HDMI cable goes straight into my LG 25" ultrawide, so no hub or splitter, just a straight hdmi cable from the monitor to the PC.

Anyone else experience something like this?
 

auntjemima

[H]ard DCOTM x2
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I've seen it once on a PC with a DVI cable. Your monitor is sending power down the cable. It's a monitor thing, as you will likely see the same result with a different cable.
 

mnewxcv

[H]F Junkie
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I've seen it once on a PC with a DVI cable. Your monitor is sending power down the cable. It's a monitor thing, as you will likely see the same result with a different cable.
interesting, and here I was going to say it was haunted.
 

Zepher

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This is the machine with the GPU removed. I also noticed that this Z97 board has an M.2 slot, pretty rare for Z97, isn't it?
it's not the fastest M.2,
1 x M.2_SSD (NGFF) Socket 3, supports M Key M.2 SATA3 6.0 Gb/s module and M.2 PCI Express module up to Gen2 x2 (10 Gb/s)

IMG_3324.JPEG
 

Zepher

[H]ipster Replacement
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I've seen it once on a PC with a DVI cable. Your monitor is sending power down the cable. It's a monitor thing, as you will likely see the same result with a different cable.
It's also weird that with the GPU removed and the PC powered down but the PSU switched on that those same two fans keep spinning.
 
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learners permit

[H]ard|Gawd
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Jun 15, 2005
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That thing needs a blow job in a bad way. Seriously I've seen dust bridge circuits before and that thing is a dirtball. Outside and air compressor for the blowout.
 
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