2011 iMac Decreasing in Performance

[mattkidd]

Im not sure whether this is simply me being paranoid but my 2011 21.5" base (i5 2.5, 12GB RAM, 500GB, 6750m) iMac which I purchased back in August feels as though the performance is decreasing and the noise emitted (probably fans) is increasing. The hard drive also sounds as though its constantly at work and sudden peaks are sometimes shown on activity monitor.

I booted up the iMac earlier and decided to straight away go into temperature monitor to check to see whether there's an abnormal readings. As shown:



The readings i am concerned about are the Power supply and the secondary heat-sink, 53 and 62. This is after less than 5 minutes of boot up? on an idle processor.

I have recently run quite a number of clean up applications such as onyx, ccleaner and Drive cleaner, which made improvements however could this actually be a hardware issue opposed to a software one. What are your thoughts?

UPDATE: After installing iStat on Dashboard the following fans speeds are shown: 1199rpm CPU, 1098RPM Hard Drive, 999rpm Optical Drive...