I was using a computer with a NVIDIA GeForce GT 640 graphics card. I got a new Dell U2414H display. The display could take only two types of inputs: DisplayPort and HDMI. The graphics card had three types of output: VGA, DVI and HDMI. How to connect them together?
I had both VGA and DVI cables for the graphics card. To connect either of these up to the display, I tried VGA-to-DisplayPort and DVI-to-DisplayPort adapters. Strangely neither of these were detected by the display. It continued to show that no DisplayPort cable was connected.
The reason for this strange behavior turns out to be that VGA or DVI cannot be upconverted to DisplayPort! Instead I used a HDMI cable and solved the problem.