DisplayPort - DVI-D cable is from CablesToGo. Their description is below.
I did a test & swapped cables/monitors. Whichever monitor is running from the DisplayPort can display the 1920x1080 but NOT 120Hz. You're hunch about passive may be the culprit.
Any suggestions on where to find an "active" DisplayPort to DVI-D cable?
nVidia Quadro 4k literature notes: Dual DisplayPort (...up to 1920x1200 @ 120Hz).
Must be my cable?
Will a DVI-D splitter work or is that just going to give me a clone on 2 monitors?
Thanks for the advice regarding config & root. I'll check permissions, etc.
Use this DisplayPort to DVI cable to connect a DisplayPort source directly to a DVI monitor or display. The passive design will support a 1920 x 1080 resolution up to 3 meters. It is VESA-compliant with transparent operation which will auto-calibrate and configure the signal for minimal configuration. Great for applications when you want to connect a newer laptop or desktop to a DVI-enabled display.
Connector 1: DisplayPort Male
Connector 2: DVI-D Male
Please Note: This DisplayPort adapter operates passively and is designed for use with dual mode graphics cards often designated with “D++”. Although the vast majority of source devices with DisplayPort are dual mode, it is recommended that you consult with your computer or graphics card manufacture to verify compatibility with passive adapters.