Hey folks, I purchased a 2012 vintage 27" Imac desktop. It came with high sierra. I bought it to go in my workshop to run a aircraft construction DVD series & my Itunes library. Apart from my Itunes library it had no other files. It used to take 45 minutes to start up. It would play music but everytime you used the mouse it would take around 3 minutes to do the task & songs would stop & start. A bit of googling & high sierra had similar problems & I was told by my local apple store this year model Imac shouldn't be running high sierra. So hours later with the wonderful help of the ozzie mac help desk I have removed high sierra & installed el capitan. So the computer is bare, no files at all & still takes 45 minutes to boot up. Before I take it to a computer repair guy as I know fear there is a more serious problem any ideas from the esteemed panel?? Thanks
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very slow 27" Imac
- Thread starter auzziemac757
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I had this same problem. The hard drive is dying.
I upgraded my iMac with an SSD and now it is much faster
https://forums.macrumors.com/threads/imac-27-inch-late-2013-hdd-ssd-upgrade.2122595/
I upgraded my iMac with an SSD and now it is much faster
https://forums.macrumors.com/threads/imac-27-inch-late-2013-hdd-ssd-upgrade.2122595/
Last edited:
Hey chscag, excellent advice. I downloaded Drivedx & it found that my hard drive is about to fail. Thankyou.
It's not necessarily a "dying" internal hard drive.
What it is, is this:
Platter-based hard drive + High Sierra = slow, slow, s_l_o_w.
Want it to run "up to speed"?
If it has USB3, buy an EXTERNAL USB3 SSD, such as a Samsung t5 or one of these:
https://www.amazon.com/exec/obidos/ASIN/B00ZTRY5IW?tag=delt-20&th=1
Then, plug it in and set it up to become the boot drive.
The iMac will boot just as easily from an external as it does from an internal drive.
Do this, and speeds should jump to around 430mbps for reads and 330+mbps for writes.
And you don't have to cut open the iMac, which runs a high risk of breaking something inside.
As for the internal drive -- just "leave it be".
Either erase it and just let it "sit there" empty, or perhaps erase it and use it for additional storage of seldom-accessed files, such as movies, that would take up too much space on the external boot SSD.
What it is, is this:
Platter-based hard drive + High Sierra = slow, slow, s_l_o_w.
Want it to run "up to speed"?
If it has USB3, buy an EXTERNAL USB3 SSD, such as a Samsung t5 or one of these:
https://www.amazon.com/exec/obidos/ASIN/B00ZTRY5IW?tag=delt-20&th=1
Then, plug it in and set it up to become the boot drive.
The iMac will boot just as easily from an external as it does from an internal drive.
Do this, and speeds should jump to around 430mbps for reads and 330+mbps for writes.
And you don't have to cut open the iMac, which runs a high risk of breaking something inside.
As for the internal drive -- just "leave it be".
Either erase it and just let it "sit there" empty, or perhaps erase it and use it for additional storage of seldom-accessed files, such as movies, that would take up too much space on the external boot SSD.
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As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
I agree. My 2010 27’ iMac started doing the same thing. I ordered a new Seagate HD to replace the original(to use as extra storage) and installed a Samsung SSD to run as the boot drive. While I was in there, I blew out 8 years of old dust and dirt from the fans, heat sinks and case as well as replacing the thermal paste on the the cpu and gpu.. I’m surprised how well the machine performs now. Slightly bummed it won’t run OS Mojave but, it is 8 years old and I’m sure High Sierra will be supported for a couple more years
Get an ssd internal drive (256GB) and increase the ram to the max and you will be shocked at how fast the computer now is. When you power up the computer you will see is already on the desktop. You may think you woke up the computer but no, that is how fast is powering up now. I mean, you will be slapping your face.
Thanks everyone for your info. I have a new hard drive on the way. When installed I will post a update of the results... here's hoping for a good outcome.
Upgrade kit:
OWC Complete Hard Drive Upgrade Kit Including Tools for all 27" iMacs 2012 & Later:
https://eshop.macsales.com/item/OWC/DIYIMACHDD12/
Instructions:
iFixit Hard Drive Replacement guide:
https://www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2639+Hard+Drive+Replacement/19643
iFixit Adhesive Strips Replacement guide:
https://www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2639+Adhesive+Strips+Replacement/24341
MacSales/OWC's How to Upgrade the Main Drive in a 27-inch iMac (2012 – Current) video:
Certainly sounds like the Hard Drive is denying and a replacement Hard Drive should be fitted as soon as possible. I thoroughly recommend a Seagate SSHD Hybrid Drive which offers improved performance over a 7200rpm HDD whilst offering increased capacity of an SSD at a lower price
https://www.seagate.com/gb/en/solutions/solid-state-hybrid/
If you did want to go with a mechanical Hard Drive then I thoroughly recommend the WD Black and is available up to 6TB
https://www.wdc.com/products/internal-storage/wd-black-desktop.html
To fit the replacement Hard Drive follow this iFixit tutorial. Don't forget to order the adhesive strips. They can be purchased from iFixit. You will need these when refitting the Display. There is an iMac opening tool included
https://www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2546+Hard+Drive+Replacement/15796
https://www.seagate.com/gb/en/solutions/solid-state-hybrid/
If you did want to go with a mechanical Hard Drive then I thoroughly recommend the WD Black and is available up to 6TB
https://www.wdc.com/products/internal-storage/wd-black-desktop.html
To fit the replacement Hard Drive follow this iFixit tutorial. Don't forget to order the adhesive strips. They can be purchased from iFixit. You will need these when refitting the Display. There is an iMac opening tool included
https://www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2546+Hard+Drive+Replacement/15796
update folks: so as the mac is just for my workshop & really only plays my itunes library & I use the dvd player for a construction series I replaced the old HD with a new WD Black 1TB & the heat sensor cable. The fitting was quite painless & took me around 40 minutes. After a re install of El Capitan my mac is running just like new. A big thankyou to chscag for advising the use of Drivedx... it worked just great in the diagnosis & thanks to all who replied with advise.