I changed the VGA cable of my second monitor (whilst my PC was powered on) and my display went off the right edge of the monitor (so I have a black bar on the left). I used the in-built controls to move it fully left but it isn't enough. I switched the cables back and this didn't return the display to normal. It might be relevant that the cable I switched to has only 14 pins but I doubt it since the native resolution of 1440x900 is what it's set to in Windows.
The Intel HD graphics software does not provide any controls to move the display on the monitor.
OS: Win 10 Pro 64-bit
Mainboard: ASUS Z170 Pro Gaming, board revision 1.04, BIOS v1904
CPU: Intel i7 6700, Stock HSF, Undervolt Offset -0.15 V, LLC 4
RAM: Corsair LPX Vengeance 2x8GB DDR4-3000 (CMK16GX4M2B3000C15)
Graphics: Gigabyte NVIDIA GeForce GTX 950 w/ 2 GB (second (affected) monitor attached to motherboard)
Sys Drive: Samsung Evo 750 SSD, 250 GB
I found the problem existed also whilst in the UEFI with the CPU graphics set to primary. I accidentally triggered the automatic image adjustment in the monitor's OSD and this fixed the problem. I didn't realise that this would help because I'd already factory reset the monitor and assumed that this would include automatic image adjustment.