Furmark loads up your video card, if it cant handle 100% load then its faulty (or psu insufficent, dust issue or whatever etc)
Its a standard compulsory test in my workshop, all computers with video cards/dedicated video MUST pass a furmark run (~1 hour)
General rule: Any computer should be able to complete any given task at any time without issue, you should never have to be "gentle" and worry about something crashing and overheating/failing thats total bs
Run the test for an hour see how it goes
What you have to understand here is there is a REASON for why you had to use system restore, dont just run things to resolve an underlying issue, find and deal with the problem