I have Windows 8.1 installed on two machines with ASRock H87M Pro4 motherboards, USB keyboards, and PS/2 mice, and both show this behavior:

When I initiate a shutdown, Windows responds with "Shutting down" and when it's done there are no lights on the PC, but the optical mouse is still lit, and left-clicking the mouse ordinarily starts the computer.

Does anyone know if this is an ASRock or Windows feature, what it's called, and how to control it? 

More info:

I understand that a PS2_USB_PWR1 mobo jumper setting can cause this behavior, but that jumper or similar does not exist on this board.

BIOS: Advanced: ACPI is set thus:

Suspend to RAM: Auto
Check Ready Bit: Enabled
ACPI HPET Table: Enabled
------
PS/2 Keyboard Power On: Disabled
PCI Devices Power On: Disabled
Wake From Onboard LAN: Disabled
Ring-In Power On: Disabled
RTC Alarm Power On: By OS   [perhaps related to MS InstantGo support?]
USB Keyboard/Remote Power On: Disabled
USB Mouse Power On: Disabled

Other settings of interest in BIOS: Advanced: Chipset Configuration: 

Onboard HD Audio: On/Off Play: Disabled already
Deep Sleep: Disabled already
Good Night LED: Auto/Enabled/Disabled (all settings failed to fix)

So I'm not seeing anything above that looks to me like it should cause this behavior.

Courtesy of Xircal at the answers.microsoft.com, I found that the behavior is fixed by setting 

BIOS: Advanced: Chipset Configuration: Deep Sleep: Enabled in S4/S5 

Courtesy of Xircal at the answers.microsoft.com, I found that the behavior is fixed by setting 

BIOS: Advanced: Chipset Configuration: Deep Sleep: Enabled in S4/S5 

• Marked as answer by Roger luMicrosoft contingent staff, Moderator 4 hours 45 minutes ago

Hi,

Glad to see your problem resolved, Hope your experience was helpful with others.