If you think it's a fan that's making the noise, you should really verify it. The hard lockup could be from overheating, due to the bad fan. Take the side(s) off the case to see if you see a fan not working. Check the PSU fan as well.
It could also be a bad HDD. If you find there are no bad fans, d/l the utility that matches your HDD mfr, a list can be found
here , and see if the HDD is not the culprit.
Hopefully, it's just your fan.