mid-2011 iMac clicking sound

If yours is an iMac 21.5-inch Mid 2011, the inside bits can be viewed in this

iFixit repair guide (logic board view, shows all internals; see section 33.)

{in this view, the optical drive and cooling fan assemblies are both removed}

https://www.ifixit.com/Guide/iMac+Intel+21.5-Inch+EMC+2428+Logic+Board+Replaceme nt/5959

{There are no parts in the upper right behind the display that would account

for the noise; however upper center, is where the hard drive is located. And

a rotational hard drive can make clicking noises; before they die. And when

they do go out, usually the symptom and results are much like you say.

•See the main section of that specific guide to see the steps to get into the

location where the hard drive lives... Note: IF 2nd HDD was installed, it may

have been placed in upper right; an option, a small 2.5" could be fitted there.}

(You may choose to seek expert help; see steps in main guide to access.)

If yours is an iMac 27-inch Mid 2011, detailed guide or takeapart image for

a model identified as such by MacTracker.ca database - is not in iFixit guide.

Seems to look alot like 21.5 inch, except small details; they share some IDs.

The graphics processor and CPUs usually are different between 21.5/27-in.

• Make an appointment at an Apple Retail Store Genius Bar
• Find an Apple Authorized Service Provider

So the suggestion is to consider an appointment at Apple store Genius to see

if they can determine a more exact cause of failure; it may be too old for them

to actually repair it. They may offer to send it out for repair to a certified shop.

-Or you could consult an Apple Authorized Service Provider; where they could

do a diagnostic a&give you a repair estimate, variable based on their findings.

The hard drive is likely candidate for replacement with new one; the AASP

can be sure to install a correct one that has a matching Temperature Sensor

so the iMac won't run fans constantly; other parts not quite right, may be a

cause of a noted annoying problem where the cooling fans default to high

and do not shut off. Apple part number replacement hard drive has sensor.

{A backup from your computer, if one exists, could be migrated to your

iMac once repaired; backups on external storage drives & those a Time

Machine utility could make, help restore a Mac. Otherwise the failed HDD

is a vortex for lost data, a costly venture if data recovery service is hired.}

In any event...

Good luck & happy computing! 🙂

Before you do ANYTHING backup the computer while you can!!!! The sound you are describing is a classic indication of a failing Hard Drive. After you have backed up the computer take it to your local Apple Authorized Service Provider to have it professionally diagnosed and likely to have the HD replaced. Once that has been done, then you can use the backup to restore your data. If you don't know of any AASPs in your area please click the following linke to begin finding one: https://locate.apple.com/country

You can use Time Machine to backup and restore or if you have a bootable clone created you can also restore from that.

Good luck!

A DIY on a 2011 isn't that difficult Assuming you have patience and skill. Make sure you buy the install kit from OWC so you get the correct tools and cables. As for a failed fan, if it's that, yes replace it! Not doing so could lead to much larger problems.

When or if you order an upgrade kit from OWC to get their SSD, be sure to ask if there

is a Temperature Sensor kit included or available as option, as the SSD will not have a

connector that matches the sensor connector from an Apple part numbered OEM HDD.

{So that possible issue can best be headed-off before you have it installed, only to find

it should maybe have had the extra sensor OWC can supply so fans don't run on high.}

Also, details about the OWC SSD products, say they do not need TRIM utility installed.

A new replacement fan should be on-hand when you take-apart the iMac; given you have

to lift the glass/display off, in order to gain access. Some models are more difficult.

Good luck in your adventure..! 🙂