Right, even with the NO-CD patch, GP4 needs a CD device, not necessary a physical one, just mount a virtual cd (there´s a lot of software to create virtual devices(Virtual CD-ROM Control Panel, MagicISO, ImDisk Virtual Disk Driver, DAEMON Tools Lite, Alcohol, etc. ), there´s no need to mount any iso, just be sure that Windows shows a cd device, that´s all.