KB 315539: Device Manager does not display devices that are not connected
https://support.microsoft.com/en-us/help/315539/device-manager-does-not-display-devices-that-are-not-connected
Device Manager displays only non-Plug and Play devices, drivers, and printers when you click Show hidden devices on the View menu. Devices that you install that are not connected to the computer (such as a Universal Serial Bus [USB] device or “ghosted” devices) are not displayed in Device Manager, even when you click Show hidden devices.
Workaround
To work around this behavior and display disconnected devices when you click Show hidden devices:
For Windows 8 and later, skip to step 3.
For Windows 7 and earlier, start with step 1:
Click Start, point to All Programs, point to
Accessories, and then click Command Prompt.
At a command prompt, type the following command , and then press ENTER:
set devmgr_show_nonpresent_devices=1
For Windows 8 and later: From Start, search for device manager, and select Device Manager from the search results.
For Windows 7 and earlier: Type the following command a command prompt, and then press ENTER:
start devmgmt.msc
Troubleshoot the devices and drivers in Device Manager.
Note Click Show hidden devices on the View menu in Device Manager before you can see devices that are not connected to the computer.
When you finish troubleshooting, close Device Manager.
Type exit at the command prompt.
Note For Windows 7 and earlier, when you close the command prompt window, Window clears the devmgr_show_nonpresent_devices=1 variable that you set in step 2 and prevents ghosted devices from being displayed when you click Show hidden devices.
If you are a developer or power user and you want to be able to view devices that are not connected to your computer, set this environment variable globally:
Right-click My Computer.
Click Properties.
Click the Advanced tab.
Click the Environment Variables tab.
Set the variables in the System Variables box.
Note Use this method only for troubleshooting or development purposes, or to prevent users from accidentally uninstalling a required device that is not connected to the computer (such as a USB device or docking station that is not connected to a laptop computer).
More Information
In Device Manager, there are two types of hidden devices in addition to the devices that are displayed:
Typical, hidden devices that are not displayed (non-Plug and Play drivers, printers, and so on)
-and-
Phantom devices that are not connected to the computer
Properties
Article ID: 315539 – Last Review: Jan 18, 2017 – Revision: 6
Applies to
Microsoft Windows XP Home Edition, Microsoft Windows XP Professional, Windows Vista, Windows 7, Windows 8.1, Windows 10
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1. Tower Totals: 2xSSD ~512GB, 2xHHD 20 TB, Memory 32GB
SSDs: 6xOS Partitions, 2xW8.1 Main & Test, 2x10.0 Test, Pro, x64
CPU i7 2600 K, SandyBridge/CougarPoint, 4 cores, 8 Threads, 3.4 GHz
Graphics Radeon RX 580, RX 580 ONLY Over Clocked
More perishable
2xMonitors Asus DVI, Sony 55" UHD TV HDMI
1. NUC 5i7 2cores, 4 Thread, Memory 8GB, 3.1 GHz, M2SSD 140GB
1xOS W8.1 Pro, NAS Dependent, Same Sony above.
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