Recently my 8 year old Mesh XP desktop has been making a noise on startup which I think I have traced to the fan at the rear of the casing. I have cleaned the fan but the noise persits but quietns after half an hour or so. Today I have noticed that when trying to access anything there is a low vibration that I believe may be coming from the hard drive. Is this how an imminent drive failure can sound?
Check ALL the fans within your case - there is one on your PSU which has a metal cover on - sometimes the fan blades can catch on this. If you find it is this unscrew this metal cover and slightly bend it away from the fan blades then re-secure it.
I'd buy a new hard drive now and clone as soon as possible. It's like driving a car, you hear a different 'noise' and you know something is wrong. You either do something about it or hope for the best. Diagnostic tools are umm OK but I wouldn't recommend taking the results as gospel.