DELL
XPS 16 9640
Core Ultra 9 185H
Sleep Mode Not Working Fix
Sleep mode not working on the Dell XPS 16 9640 Core Ultra 9 185H means the laptop does not enter sleep when the lid is closed or after the configured sleep timeout, the laptop wakes immediately after sleeping, or Windows does not wake from sleep correctly. The XPS 16 9640 uses Intel Meteor Lake-H with Intel Arc integrated graphics and optional NVIDIA discrete GPU, which introduces specific sleep state requirements for proper S0 Low Power Idle (Modern Standby) operation.
Sleep enters but wakes immediately
A USB device, network adapter, or scheduled task is waking the system. Run powercfg /lastwake to identify the wake source. Disable Wake on LAN in BIOS and Device Manager power settings.
Lid close does not sleep
Check Power Options → Choose what closing the lid does. The lid close action must be set to Sleep for battery and plugged-in modes. Dell Command Update may have reset this to Do Nothing.
Fix: Update Intel ME and BIOS via Dell Command Update
Download and run Dell Command Update from Dell Support to install all critical and recommended updates. The Intel Management Engine firmware and BIOS updates for the XPS 16 9640 contain Modern Standby sleep state fixes for the Core Ultra 9 185H Meteor Lake-H platform. Without the latest Intel ME firmware, Modern Standby can fail to transition to deep sleep states and cause the system to wake from sleep spuriously or fail to enter sleep at all.
Per Fadli Hamzah, video production professional using Dell XPS 16 9640: “XPS 16 9640 would not sleep after closing the lid. Dell Command Update had several pending BIOS and Intel ME firmware updates. After installing all updates and restarting, sleep mode worked correctly on lid close.”
Fix: Disable Wake-on-LAN and USB Wake
In Device Manager → Network Adapters → Killer Intel Wi-Fi → Properties → Power Management, uncheck Allow this device to wake the computer. Repeat for the Intel Ethernet adapter if present. Also restart and press F2 for Dell BIOS → Power Management → Wake on LAN and set to Disabled. Run powercfg /devicequery wake_armed in an elevated CMD to list all devices that can wake the system, then disable Wake permissions for non-essential devices.
Fix: Reset Power Plan to Balanced
Open an elevated CMD and run powercfg /restoredefaultschemes. This resets all power plans to Windows defaults and clears any corrupted sleep timer or hibernate settings. After restoring, set the active plan to Balanced. Dell XPS 16 9640 may ship with a Dell-customized power plan that has sleep timers disabled or set to very long intervals for performance scenarios.
Frequently Asked Questions
Why does the Dell XPS 16 9640 not go to sleep?
Sleep timeout may be disabled in the power plan, lid close action may be set to Do Nothing, or outdated BIOS and Intel ME firmware are preventing Modern Standby from functioning correctly. Update via Dell Command Update and check Power Options lid close and sleep timer settings.
Does Dell XPS 16 9640 use S3 or Modern Standby sleep?
The XPS 16 9640 uses Modern Standby (S0 Low Power Idle), not traditional S3 sleep. Modern Standby keeps the system in a low-power state while maintaining network connectivity for background tasks. Run powercfg /a in CMD to see which sleep states are available on the system.
Why does Dell XPS 16 9640 wake from sleep by itself?
A USB device, network adapter Wake on LAN, or scheduled maintenance task is waking the system. Run powercfg /lastwake to identify the most recent wake source. Disable Wake on LAN in BIOS and in Device Manager Power Management for Killer Intel Wi-Fi. Disable scheduled maintenance wake timers in Power Options Advanced settings.
Does connecting a Dell Thunderbolt dock affect XPS 16 9640 sleep?
Yes. Thunderbolt docks with USB hubs, Ethernet, and DisplayPort outputs can prevent the system from entering deep sleep states if the dock is powered and connected. If the XPS 16 9640 cannot sleep with the dock connected, this is a known Modern Standby behavior with powered Thunderbolt docks. Disconnect the dock before closing the lid if uninterrupted sleep is required.
Conclusion
Sleep mode not working on the Dell XPS 16 9640 Core Ultra 9 185H is fixed by running Dell Command Update to install the latest BIOS and Intel ME firmware, checking Power Options lid close action is set to Sleep, and disabling Wake on LAN in BIOS and Device Manager. Run powercfg /lastwake to diagnose wake sources if the system wakes immediately after sleeping. The XPS 16 9640 uses Modern Standby and requires current firmware for proper sleep state transitions on the Meteor Lake-H platform.
Ryan holds a Computer Science degree and has over 20 years of hands-on experience with PC hardware, software, and driver troubleshooting. He is the author behind softwaredriverdownload.com, where he helps everyday users fix driver issues quickly and accurately. Ryan has personally tested most of the fixes on this site across a range of Windows 10 and Windows 11 machines.
Leave a Reply