I am also crashing when I once had no issues. Valmod now crashes straight to the desktop before even loading in items. Fresh install also does this, I have 32 gigs of ram, galax gtx 1080 ti and 7700k cpu, ran off of an ssd. So I am 100% sure my pc can handle the modpacks I am attempting to run.
EDIT: interestingly enough, only simple mode crashes the modpacks, once I switch to advance and do it all the long way it seems to work o.o