Loud noise on startup

[pvknbd]

Ok so I had my computer on for almost a week now and everything was ok then I turned it off and went to sleep and turned it on in the morning today and as soon as I did it starting making a loud noise I'm not 100% sure how to describe it does not sound like some fan is hitting a wire or something just a loud noise now I'm not 100% sure where it's coming from I think it may be coming from the power supply because whenever my computer is on I can hear a slight ticking noise from the bottom of the case which is where the power supply is (atleast I think thats where it's coming from) I've had this same problem before but just holding down the power button and turning it back on again usually fixes the problem but this time after the 3rd time of holding the power button and turning it back on it stil makes the loud noise and I don't want to do it again so I was wondering what can be the problem and how can I fix it and I don't want to replace the power supply unless I'm 100% sure thats the problem

[dragoon20005]

open up the casing an hear where is the source