Re: Update to 190.42 breaks Xinerama AND TwinView!
desperadus, "notebook OEM" here does mean Lenovo. It sounds like Lenovo simply didn't include an EDID in with the second monitor and instead customized the Windows drivers to force a particular resolution. Your best bet for getting that monitor to work reliably is to contact Lenovo and ask them for a copy of the monitor's EDID, or extract it from Windows using one of the free Windows EDID tools, and then load it into the NVIDIA Linux driver using the CustomEDID option.
Please keep the conversation in this thread civil.