I forced the 2004 update with the Windows10Upgrade9252.exe update tool on one of my computers, and it seemed to take longer than I thought it should have. When it rebooted, my secondary hard drive was missing and I couldn't get it working again, so I had to do an image restore. The obvious thing to look at is the controller driver, but it was there. And as well as that, my primary and tertiary drives were using the same Intel(R) ICH10R SATA AHCI Controller and still working. I wonder why forcing the update can cause compatibility issues as opposed to waiting for it via Windows Update.