Apologies that you are having difficulties with your xps 9550.
So, does the computer have flickering problems while playing games? or does it do it all the time like for email and internet browsing?
Have you tried the current driver, you can un-install and re-install the driver, make sure your chipset and BIOS drivers are up to date as well.
If that's not working, then try running a systems diagnostics by pressing F12 at startup, or by running Support Assist. Make a note of any error messages and contact Tech support for troubleshooting and possible resolution. You can contact Tech Support at 1-800-624-9896 or 1-800-288-4410, or you can initiate a chat session http://dell.to/2v4snVm