I have a couple of old PCs that I use on my electronics workbench; an Acer Aspire X3990 and an Acer Aspire X3995 both running Windows 10 version 1607 (originally they ran Windows 7 Home Premium, upgraded in-place to Windows 10).

Any attempt to upgrade these systems to a newer Windows 10 fails; the screen just goes black and the system hangs. No diagnostics whatsoever. After many frustrating attempts I decided to do a “clean” install.

I extracted the Product Key from the running OS using the free ProduKey utility. Then, I downloaded the Windows 10 Home installation media and created a bootable USB stick.

This time, the installer threw an error before hanging: “clock watchdog timeout”. Google finally came up with a few relevant links (tenforums.com and hardforum.com) that pointed me to the WiFi add-on card.

I never used WiFi on these PCs, so I pulled the card out and lo and behold: Windows 10 installation finally succeeds without problems!