XPS 8900 with the original 1 TB hard drive, and a 5 TB drive used as storage and backup. Last night I did a clean install of Windows 10. I installed it on a new 250 GB SSD. I had disconnected the other 2 drives while installing Windows. After the Windows installation I reconnected the drives. Everything was good, all three drives showed up in Windows.
This morning I went to Dell's website to see if any drivers needed updating. Dell's system detect found two drivers: Intel Rapid Storage Technology Driver and Management Console, and Intel I2xx/825xx Gigabit Ethernet Network Controller Drivers. I installed them. After that, the 5 TB drive disappeared. It still showed up in the BIOS, but not in Windows. Nowhere, not in disk management, nowhere. Fortunately, before installing the drivers, Windows created a restore point. I went back to that restore point, and the drive reappeared.
Everything's working fine now, but I'm wondering if I'll run into problems without those two updates? I know I could install just one of the drivers first, to find which one's causing the problem, but thought I'd ask here first.