The GeForce GTX 745 cannot drive a dual monitor daisy chain because that video card does not have a DP or mDP out port.
The XPS 8900 onboard DP out port cannot drive a dual monitor daisy chain.
There are three options for video port usage on the XPS 8900, all based on what you choose in the Bios- Display;
* Set it to Multi Display Disabled, Primary Display Intel HD Graphics
- Remove the added PCIe x16 video card from the system
- Use either the onboard HDMI out or onboard DisplayPort out
* Set it to Multi Display Disabled, Primary Display Nvidia HD Graphics
- Use the added PCIe x16 video card as your only Graphics
- The onboard HDMI out and onboard DisplayPort out are turned OFF
* Set it to Multi Display Enabled, Primary Display AUTO
- The onboard HDMI out is Primary
- The onboard DisplayPort out is Secondary
- The added PCIe x16 video card ports are Tertiary, Quaternary, Quinary