Does the Dell XPS 8930 leave room for PCIe cards and a better cooler?

Yes, the XPS 8930 has two PCIe x1 slots for expansion like a Wi-Fi card or extra USB ports, and the CPU cooler can be upgraded to a standard LGA 1151-compatible aftermarket unit if the stock cooler is too loud or the machine runs hot. It’s not a wide-open chassis, but Dell kept the important bits standard.