U2414H, you cannot upconvert computer VGA to U2414H DP/mDP

Hi,

I've purchased this monitor 3 days ago. My computers configuration is as follows:

• IBM ThinkCentre Core 2 Duo 6600, ATI 4500 video card (outputs: 1 DVI, 1 HDMI, 1 VGA),   ...
• The previous monitor: LG 1960TR was connected via the DVI slot.

At first I've tested both HDMI inputs of Dell U2414H, and the results are excellent (as expected). The issue is, that the computer's HDMI output is usually connected to the LCD TV, and I wanted to make use of one of the Display Ports. I've tried three different cables/adaptors:

1. Display Port male to DVI female adaptor - to be connected to the DVI cable (attached to the video card DVI output)
2. Display Port male to DVI male cable - directly connecting the Dell U2414H to the computer's video card (DVI).
3. Display Port male to HDMI male cable - directly connecting the Dell U2414H to the computer's video card (HDMI).

All of these tests failed - the video source wasn't detected by the Dell U2414H monitor. Is there a proper solution ?

Thanks,

Zeev