Diagnosis
The monitor's Power Saver mode is detecting no signal change and entering sleep. The signal from the PC is static or not recognized as 'active'.
How to Fix It
Adjust two settings. First, on the monitor: Press the menu button, go to 'Others' -> 'Power Saver'. Set this to 'Off'. This disables the monitor's own motion detection. Second, on your Windows PC: Go to Settings -> System -> Power & Sleep. Set 'Screen' and 'Sleep' timers to 'Never' while plugged in. This hands full control back to the OS.
If That Didn't Work
The issue may be the graphics driver's power management. For NVIDIA: Open NVIDIA Control Panel, go to 'Manage 3D Settings' -> 'Global Settings', find 'Power Management Mode' and set it to 'Prefer Maximum Performance'. For AMD Radeon Settings: Go to Gaming -> Global Settings -> Power Efficiency, and turn it Off.
Heads Up
With Power Saver 'Off', the monitor backlight will remain on whenever it receives a signal, regardless of content. This increases power consumption and potential for image retention (temporary), though the IPS panel is resistant to burn-in.