Pc Won't Fully Shutdown? Gigabyte Ep45-ud3r

I'm trying to shut down my system like I've always done on my other Windows 10 PC's - right click windows logo at bottom right of screen then select 'Shut down' in the menu. Also I get the same result via momentarily pressing the power button - the display shows the word 'Shutting Down' with the little circle image going round and round momentarily, then the display goes dark. Monitor/TV then displays 'no signal'. But the case and CPU fans stay running, the power LED stays illuminated, the HDD activity light goes out but the USB external drive (if connected) stays active.
It won't wake via mouse, keyboard, power button etc. It will remain in this state indefinitely until I depress the power button for a few seconds forcing shutdown.

* Settings in 'Control Panel > Power Options > System settings > Change settings that are currently unavailable': The 4 boxes for 1-'Turn on fast startup (recommended)', 2-'Sleep', 3-'Hibernate' and 4-'Lock' are all UNchecked.
In Power options > advanced settings:
*Turn off hard disk after 3600 minutes
*Sleep after = never
*Allow Hybrid sleep = Off
*Hibernate after = Never
*Allow wake timers = Disable
*Power button action = Shut down
*Sleep button action = Do nothing
*PCI Express > link state power management = Off
* In BIOS > advanced settings, Quick Start is disabled

I've tried a different SSD and a different HDD with the same results.
I've replaced the PSU with a new Corsair 750w unit.
I've replaced the RAM with 4 new sticks (4x2GB DDR2 1066)
Startup time is approx 37 seconds. If I enable fast startup in 'Power Options> 'Change settings that are currently disabled', then the time shortens to ~30 seconds. So apparently 'Fast Startup' is indeed functional but I have it set for disabled now.
Motherboard specs, manual, etc is here:
https://www.gigabyte.com/us/Motherboard/GA-EP45-UD3R-rev-11#support-manual

System specs are:
Antec Atlas ATX case
Gigabyte GA-EP45-UD3R mboard
Core2 Quad Extreme QX6850 CPU
Corsair RM750x PSU
Windows HM X64 OS
G Skilll 4x2 GB DDR2 1066
GeForce 8400 GS GPU
PNY CS900 2.5" SSD 480GB primary
WD HDD 1TB storage

What else should I look for to solve this partial shutdown issue?
Thanks for any help!

 

I have been living with a similar situation for a number of years. After shutting down the pc I switch off the power supply manually. Then I turn it on ready for the next boot...
When I shut down the same pc after running a linux OS it turns off correctly. I am confused and so look forward to other replies to your thread.
Good luck,
s.

 

that's a really old motherboard. I think I had one of those maybe 6 or 7 years ago.
have you changed the cmos battery lately? maybe it's dead and causing the mobo to flake out?

 

Sometimes an OS update can become 'stuck', or just need to be installed.

Do a hard shutdown......hold your devices power button down for 5 secs or so, and ensure all lights, fans etc go down.

After a few minutes, power up again......If you can successfully boot to windows, cmos should be ok and its most likely a software issue.

After powering-up, update Windows manually through the control panel, 'Updates & Security' > 'Check for updates'
Be patient!

 

Yeah, good luck I have two identical Dell PCs that I move one hard drive between, one system will power off, the other will not, I've matched the BIOS settings and of course the OS is the same in both.

 

Strange thing happened in my instance of this.
If I started up the machine into a linux OS it would correctly shut down.
Fans everything stopped.
Rebooting into a USB drive and waiting for everything to install just to turn it off didn't seem worth the effort.
It's an old motherboard. A little eclectic...
s.

 

Something is preventing the PC from shutting down and the test is to generate a power report. start an administrative CMD or Powershell window and type POWERCFG -ENERGY which will generate an energy report that lists what is causing the problem. You do; though, generally need to copy the report someplace else (like your desktop) in order to view it.

 

The report is over here:
C:/Windows/System32/energy-report.html

 

Yeh well, never come across this before.....same HD => same OS on identical devices?

Im not sure, but could it be a slight firmware config diff on each mobo?

Long shot: Have you tried flashing both bios devices from the same file?

It may sound silly, but are you utilizing identical sata ports for the HD on each mobo?

 

I've done everything previously suggested until I got to this 'energy report'. I'm not sure what I'm looking at but I don't see anything that would prevent the machine from shutting down correctly. Am I missing something?
I don't see how to attach this html file so I'll upload a .txt file:

 

Unplug all USB devices (excluding mouse and keyboard) before shutting down.
Try a different power plan.

 

2 ways to disable the 'selective suspend' for USB hubs: via the Power management tab for each USB hub in Device Manager, or in the Advanced settings for your Power plan:

 

The only USB device (other than mouse/keyboard) plugged in was a Bluetooth dongle which is now unplugged. Now using 'Balanced' power plan with USB Selective Suspend Setting 'Disabled'. = Issue is the same - won't shut down fully.