My iMac has started to make a noise, is the fan the possible problem?

Mr Cleaver – Sale – iMac A1312 -My iMac has started to make a noise, is the fan the possible problem? 29/08/15

System taken into workshop 28/08/15
Take scale on these types of issues can not be determined at this stage
Extensive hardware tests on all hardware & software currently being carried out 6PM 28/08/15
7PM 28/08/15 – Motherboard – OK
7PM 28/08/15 – Memory – OK
8PM 28/08/15 CPU – OK
3PM 29/08/15 – Software corruption type is established – I still need to determine the cause if I am to carry this out correctly
5PM 29/08/15 – Viruses found, Trojans found malware found…..
12PM 30/08/15 – Extensive Hard Drive tests have been carried out and corruption from the viruses is now apparent;

The original issue of the abnormal noise coming from the cooling system has not been found

Summary

The issues above that we can find, is more than likely to be the cause of the system fan being noisy due to bad files over using the resources
It is now a case of whether you would like me to carry out this repair which I do regard as very urgent and have the system back either tonight or tomorrow and should the noisy fan return, I can take a visit at your home and carry out some additional work as there may be a certain program combination or other configurations variables which differ from being here at the workshop, but hardware wise the fans are stable and working efficiently
More than likely faults that have been found are related to this intermittent issue and resolving this will resolve your problem but if these are not looked into your system will sustain far more damage to its core software in the near future

For the repair to be carried out, here is an itemised list of what needs to be done;

Manual removal of all damaging software – £65
Repair of the software already damaged – £20-£70 dependant on severity, I will not know the severity until this is started
Preventative action (not necessary for the actual repair but highly advised so it doesn’t end up in this situation again) £40

£30.00 Investigation Fee, should you not wish for us to carry out the repair