A boot drive...that is not used as a boot drive...does not have the power to infect anything. It's just another container with a set of files on it, none of which have no power to do anything other than to sit in place while connected as a storage drive.
All .exe and other files (.dlls and drivers) which might trigger activity when associated with the O/S...have no association other than as data items when connected as a secondary drive. The relationship with the infected O/S is of no consequence, in such case..since the infected O/S is not active as a secondary drive.
I have a triple boot (XP, Win 7, Win 10) and I have a home network with 2 other computers. If my XP install became infected...it could conceivably pass said infection to other networked systems via the O/S relationships in a network...but it could not pass the infection to my Win 7 or Win 10 installs...since only one is operative at a single moment in time.
A drive connected as a non-boot drive...is just a storage container.
Edited by hamluis, 27 December 2017 - 09:33 AM.