Switching from Ubilinux to Windows 8.1!!

guzzarish

I have several Up boards running Ubilinux, and need to install Windows 8.1 on one of them. When I boot from the Win 8.1 ISO usb stick, I get an immediate message:

Recovery
Your PC needs to be repaired
There isn't enough memory available to create a ramdisk device
Error code 0xc0000017
[. . .]

I suspect this has something to do with UEFI and I'll need to change to BIOS to allow me to load a different OS, but I'm not sure what should be changed. Suggestions?