Fans not stopping after powering off the computer.

[rpggirl82582]

Ok I have a weird one.

I have a corsair case (Graphite Series Spec 03 Blue Case) and a build with the following specs

Operating System
Windows 10 Home 64-bit
CPU
Intel Core i7 @ 3.60GHz
Kaby Lake 14nm Technology
RAM
32.0GB
Motherboard
ASRock H110M-DGS R3.0 (CPUSocket)
%1 Chipset
Graphics
ASUS VS228 (1920x1080@60Hz)
2047MB NVIDIA GeForce GTX 1060 6GB (MSI) 31 °C
Storage
223GB KINGSTON SUV400S37240G (SSD) 26 °C
931GB TOSHIBA DT01ACA100 (SATA) 28 °C
1863GB Seagate ST2000DM001-1CH164 (SATA) 29 °C
3726GB Seagate BUP RD SCSI Disk Device (USB (SATA)) 28 °C
3726GB Seagate BUP RD SCSI Disk Device (USB (SATA)) 28 °C
Optical Drives
hp CDDVDW TS-H653R
Audio
Realtek High Definition Audio

My problem.
The other night I shut down the computer via the external power button and I noticed that the blue led fan in the front of the case was still running (as were all the other fans including the one on the cooler)and so I restarted the computer and attempted shut down via Windows shutdown same difference. so for a goof I unplugged the power supply. and this is where it got odd, the fans were still running with the power cord unplugged. Now I'm stumped.

 

[zoltan.boese]

Well, there are capacitors storing some energy, shorty after unplugging the PSU, there will still be some juice left in the system.
Still, powering down your system should ensure, that no power will be supported to the fans any longer. I suppose, that the blue lit fan is connected directly to the power supply. (Tell me so if it is plugged onto the mortarboard!)
Try to borrow a power supply, swap it with yours and let´s see if the problem is solved!
If you are looking for a new power supply unit, you will need at least 450W. The budget favourites are the Corsair CX 450 and the Seasonic 520W m12ii-520.

 

[rpggirl82582]

I think I may have stumbled on what is going on. it was computer dusting day so I started removing all the cords from the back. The second I unplugged the HDMI cord from my graphics card the power completely turned off. It appears that power was running back through the hdmi cable and keeping some things on.

 

[zoltan.boese]

I think I may have stumbled on what is going on. it was computer dusting day so I started removing all the cords from the back. The second I unplugged the HDMI cord from my graphics card the power completely turned off. It appears that power was running back through the hdmi cable and keeping some things on.

This is getting interesting! There should be diodes there preventing back current. What make and model do you use?
Was the HDMI plugged into your graphics card or the motherboard? And where was the fan cable connected?