The monitor worked fine until I installed a fresh new x64 Windows 10 Pro (was x32 before). My graphics card is an ATI Mobility Radeon 4500 HD series, with drivers for Windows 8 x64, the newest ones from AMD's site. The monitor is an Acer X223W S, with only a single VGA port. My cable is fine for sure.
The monitor is detected as a Generic Non-PnP monitor, and the desired resolution is not on the list (1600x1000, if I recall correctly). I tried the CRU to set a resolution but it failed, I also tried different drivers for both the display adapter and the monitor, for the latter I found the original driver, but installing it didn't help. Rebooting doesn't help either.