My 4 y.o pc has been making loud grinding noices during startup which cease afterwards. There is no performance issues with it. However all I could do to check was a 3dmark benchmark test. I tried opening the case to listen, but I couldnt identify whether the sound was coming from fans(hopefully) or hardware. Should I keep being concerned about this? What else can I do?
Most likely this is caused by fan bearing being worn. If you have any case fans and they came with sleeve bearings then those are the most likely problem. The course of action would be to replace those fans.
if the hard drive was faulty in would make a grinding noise all the time.
You may have noticed that some fans go fast at boot up then slow down , check the gauze dust traps on the fans to see if they need cleaning