Dell has no Windows 8/8.1 drivers for the XPS 8100. Windows 8.1 has a newer driver than the old drivers Dell offers for Windows 7. Their driver is from 2010. I would not use any Dell update utility as they won't take into account a Windows 8.1 install. The driver Windows 8.1 includes is even later than the one listed on the Broadcom website: [URL] It should work fine. It could be good to install the latest Intel Chipset drivers however to help your system run more stable: [URL]  
I have a Studio XPS 8100. I have had problems (corrupted files) with OEM Win7 Ult and switched To Win 8.1 Pro. Since then  my Ethernet adapter (Broadcom NetLink Gigabit Ethernet) gets disabled occasionally for no reason that I can pinpoint. The currently installed driver is version 15.6.1.2. When I ask Dell to check my driver for an update, I think it assumes that I am still running Win7 and recommends version12.2.2. Was the currently installed version installed by Win8.1? Should I revert back to version 12.2.2 as recommended by Dell?  Thanks in advance pasparawlu  
Ethernet Adapter Driver for Win8.1