What do I need to buy to connect old iMac (2011) to Dell XPS so I can work on a large screen? The iMac has a thunderbolt port and I've been told that a thunderbolt cable and a USB C connector will enable this but having read the comments online I am not so sure.
What you need is an external display for the Dell, it simply will not connect to your iMac. Your iMac is a computer and not a display for a PC.
A USB port is not enough. The 2011 iMac needs Thunderbolt. There are no adapters, cables, or converters that can make Thunderbolt from a non-Thunderbolt device.
AFAIK, this would only be possible with using another Mac.
Ref: Use your iMac as a display with Target Display Mode - Apple Support
Thanks for your reply. I want to display the Dell screen onto my larger iMac screen (not the other way around). I have a connector to the Dell which has a USB port.
You can not use a Dell XPS laptop as an external display for your Mac or anything else. It does not have a video input of any kind.
Connect old iMac (2011) to Dell XPS so I can work on a large screen
