|"All the fans appear to be working except for a very small fan on the bottom side of the video card"|
"I dont believe this is an issue of overheating"
Why would it not be an overheating issue? The fan is there for a reason. If it's not working, the GPU is most likely overheating.
Try letting the system cool down for a while. If you have a small desk fan, remove the side panel & position the fan so that it blows directly into the case, then see if you can boot into windows normally. If that "solves" the problem, remove the card & check the fan...see if it spins freely or not. It may just be dust clogged, then again, it may have burned out. If the fan is bad, you'll either have to replace it or replace the entire card. If it's an old card anyway, now may be a good time to upgrade.