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I second the advice of EugW in reply #15 above.

The "slowness" is not so much the RAM.
It's the platter-based hard drive inside.
Platter-based HDD's can't run recent versions of the Mac OS very well.
Yes, the OS "runs" ... but it feels to the user more like it's "walking". ;)

It's not worth spending much on a 2011 iMac.
Your main problem here is you can't use USB because the 2011 has USB2 (not USB3).

A smaller-sized thunderbolt drive (250-256gb) will do the job.
Even so, these cost more than a USB3 drive of equivalent capacity.

But... for a 2011 Mac... it's "the only way" -- other than opening the case and putting an SSD inside. Not sure if you're willing to try that.

Final thought:
How's your budget?
It looks like there could be a few new iMacs for 2018 on Tuesday (I wasn't expecting them until next year)...
 
If the NV RAM battery is missing or completely dead, your settings are not saved—easy to diagnose. It has no effect on a Mac that is running; only when booting up.

A weak battery can cause a few other problems on boot up including a dark screen. The way I normally diagnose this is to pull the battery or replace it—either is better than a battery that's too weak.

Mac Pros need to have the battery replaced every 5 years—cheese grater and trash can. iMac batteries tend to last longer with 7–9 years not uncommon.

Intel Macs all come with the BR2032 installed except for the portables. Its temperature range is wider than the common CR2032 medical battery. I have no problem using a CR2032 in a 2011 and later iMac if there's no HHD inside—otherwise, I'll install a BR2032. Before 2011, a CR2032 is fine in any iMac.

You can get a single BR2032 for $7.90 or three for $8.05 on Amazon.

The CR2032 can be found in any drug or hardware store. Medical devices specify name brand batteries. I figure that, since I expect them to last for many years, that's a good procedure to follow. I do not buy the $1 generics.

Anyway, if I'm cracking open an iMac that's over 3 years old, the battery gets replaced.
[doublepost=1540572068][/doublepost]
Still intrigued about replacing the battery and what the benefits are in case I do decide to add an internal SSD.
 
I second the advice of EugW in reply #15 above.

The "slowness" is not so much the RAM.
It's the platter-based hard drive inside.
Platter-based HDD's can't run recent versions of the Mac OS very well.
Yes, the OS "runs" ... but it feels to the user more like it's "walking". ;)

It's not worth spending much on a 2011 iMac.
Your main problem here is you can't use USB because the 2011 has USB2 (not USB3).

A smaller-sized thunderbolt drive (250-256gb) will do the job.
Even so, these cost more than a USB3 drive of equivalent capacity.

But... for a 2011 Mac... it's "the only way" -- other than opening the case and putting an SSD inside. Not sure if you're willing to try that.

Final thought:
How's your budget?
It looks like there could be a few new iMacs for 2018 on Tuesday (I wasn't expecting them until next year)...
Have forked out £55 for 8GB of RAM to see how that improves things. Can get an internal 250GB SSD for another £50 plus about £25 for the installation kit, whereas best price I can find for an external thunderbolt 250GB SSD is £142. If I could get the external SSD for under £100 then would be tempted with that option to avoid having to open up the iMac.
 
These are really easy to open.

A few tips:

The bezel screws are two different lengths and the arrangement is not symmetrical along the bottom — pay attention to which screw came out of which hole.

When you get the bezel loose, do not disconnect the mic connector at the top of the screen. Lay the iMac on its back and move the bezel 180° so it's on the bench and connected by the cable. This will save a major hassle putting it back and ensure the microphone works then you're done.

You do not have to remove the screen.

After you remove the screen screws, lift the top enough to work inside. You'll have to unplug a thin wire to lift it high enough. I use the box the SSD comes in to hold the screen high enough. There's plenty of work inside.

If you didn't buy the heat sensor from OWC, read up on how to short the original temp sensor or you will have fan issues.

After you've installed the SSD, lower the screen part way and pull towards the top just enough to expose the bottom edge. Lift the bottom to expose the NV RAM battery — you may have to remove a cable or two — and replace it.

To replace the battery, do not pry up or you'll break the lip. Instead, push the battery against the leaf spring to clear the lip and lift the edge to remove—use a thin screw driver or toothpick through the slot if needed. Replacing is easy—push the edge against the spring and it will pop in. If you break the lip on the holder anyway, use a small piece of styrofoam between the battery and the screen to hold the new one in place.

Now replace the screen in the lower slot before lowering the top in place.

It's easy to drop the screen screws into the case. Make certain there is a thread on the other side of the hole (not all holes do).

Approach the holes at a 45° angle opposite the glass magnets. Trust me on this one.
 
These are really easy to open.

A few tips:

The bezel screws are two different lengths and the arrangement is not symmetrical along the bottom — pay attention to which screw came out of which hole.

When you get the bezel loose, do not disconnect the mic connector at the top of the screen. Lay the iMac on its back and move the bezel 180° so it's on the bench and connected by the cable. This will save a major hassle putting it back and ensure the microphone works then you're done.

You do not have to remove the screen.

After you remove the screen screws, lift the top enough to work inside. You'll have to unplug a thin wire to lift it high enough. I use the box the SSD comes in to hold the screen high enough. There's plenty of work inside.

If you didn't buy the heat sensor from OWC, read up on how to short the original temp sensor or you will have fan issues.

After you've installed the SSD, lower the screen part way and pull towards the top just enough to expose the bottom edge. Lift the bottom to expose the NV RAM battery — you may have to remove a cable or two — and replace it.

To replace the battery, do not pry up or you'll break the lip. Instead, push the battery against the leaf spring to clear the lip and lift the edge to remove—use a thin screw driver or toothpick through the slot if needed. Replacing is easy—push the edge against the spring and it will pop in. If you break the lip on the holder anyway, use a small piece of styrofoam between the battery and the screen to hold the new one in place.

Now replace the screen in the lower slot before lowering the top in place.

It's easy to drop the screen screws into the case. Make certain there is a thread on the other side of the hole (not all holes do).

Approach the holes at a 45° angle opposite the glass magnets. Trust me on this one.
How do I avoid the fan speed issues that can be a problem if you add an internal SSD?
 
How do I avoid the fan speed issues that can be a problem if you add an internal SSD?

Beginning late 2009, the HDD has a temp sensor that's part of the harness and plugs into the drive. The Seagate and WD HDDs used different ones. Worse, for years you could not buy a replacement HDD with the plug for that sensor (that changed). Pulling that cable will cause the fans to run full on 100% of the time.

You have three options:

OWC makes a temp sensor that you stick onto the SSD (or replacement HDD). It's integrated into a wiring harness. The 2009–10 version is not interchangeable with the 2011–current. This is the ideal solution. I think that OWC charges the same as Amazon:
https://www.amazon.com/OWC-Digital-Thermal-Sensor-Upgrade/dp/B00J42AFUA

You can short the cable in the original wiring harness. This leaves no sensor for the SSD. I don't know which wires need to be crossed because I always install the OWC harness. If the SSD overheats, most have a thermal slow-down mode—in any case, no fan will come on to cool it.

If you pull the sensor cable without doing either of the above, you must control the fans manually. There's freeware. You pull up a panel to monitor the temperature and adjust the fans as needed. Ok... BTW, the fans will run at full speed during startup till the app loads. When I did my 2010, OWC was backordered on the 2009–10 sensor and I had to do this for two weeks. Never again!
 
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Beginning late 2009, the HDD has a temp sensor that's part of the harness and plugs into the drive. The Seagate and WD HDDs used different ones. Worse, for years you could not buy a replacement HDD with the plug for that sensor (that changed). Pulling that cable will cause the fans to run full on 100% of the time.

You have three options:

OWC makes a temp sensor that you stick onto the SSD (or replacement HDD). It's integrated into a wiring harness. The 2009–10 version is not interchangeable with the 2011–current. This is the ideal solution. I think that OWC charges the same as Amazon:
https://www.amazon.com/OWC-Digital-Thermal-Sensor-Upgrade/dp/B00J42AFUA

You can short the cable in the original wiring harness. This leaves no sensor for the SSD. I don't know which wires need to be crossed because I always install the OWC harness. If the SSD overheats, most have a thermal slow-down mode—in any case, no fan will come on to cool it.

If you pull the sensor cable without doing either of the above, you must control the fans manually. There's freeware. You pull up a panel to monitor the temperature and adjust the fans as needed. Ok... BTW, the fans will run at full speed during startup till the app loads. When I did my 2010, OWC was backordered on the 2009–10 sensor and I had to do this for two weeks. Never again!
Thanks, I really appreciate all the advice. If I was just adding an SSD and keeping the existing HDD would I still need the temperature sensor cable?
 
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I am in the same boat.
What is a good External Thunderbolt SSD under $250?
How do I connect a Thunderbolt3/usb-C SSD to 2011 imac with Thunderbolt 1/2 socket? I cannot find the adaptor.

I need a reverse of this ....

2prh4r8.jpg
 
Last edited:
Thanks, I really appreciate all the advice. If I was just adding an SSD and keeping the existing HDD would I still need the temperature sensor cable?

First test performance with the new RAM, you might not need an SSD and the upgrade cost might be better spent as an addition to the new-computer fund for whenever you do buy a newer model.

Anyway, back to the question: OWC neither includes the thermal cable nor shows a thermal cable installation on their upgrade video for the SSD to 3rd SATA port upgrade. Therefor I would logically infer that no thermal cable is not required (although you could contact them directly if you want a stronger assurance.)

Speak of which, after having watched the upgrade instructional video I'd like to revise my difficulty estimate for the extra SSD upgrade upwards. If you haven't yet seen the videos I'd suggest watching them. The 'HDD Drive Install' is for replacing the HDD with either a new HDD or SSD. The 'SSD Installation' video is for adding an SSD without replacing the HDD or optical drive. https://eshop.macsales.com/installvideos/imac_21_mid_2011/


I am in the same boat.
What is a good External Thunderbolt SSD under $250?
How do I connect a Thunderbolt3/usb-C SSD to 2011 imac with Thunderbolt 1/2 socket? I cannot find the adaptor.

For USB-C you can't. For a true Thunderbolt3 SSD simply plug the adaptor into the drive and run a Thunderbolt 1/2 cable from the adaptor to the iMac.

Otherwise if an eSata or USB 3.0 SSD is close enough then I guess you could use something like this:
https://www.apple.com/shop/product/HGC82ZM/A/kanex-thunderbolt-to-esata-usb-30-adapter
 
First test performance with the new RAM, you might not need an SSD and the upgrade cost might be better spent as an addition to the new-computer fund for whenever you do buy a newer model.

Anyway, back to the question: OWC neither includes the thermal cable nor shows a thermal cable installation on their upgrade video for the SSD to 3rd SATA port upgrade. Therefor I would logically infer that no thermal cable is not required (although you could contact them directly if you want a stronger assurance.)

Speak of which, after having watched the upgrade instructional video I'd like to revise my difficulty estimate for the extra SSD upgrade upwards. If you haven't yet seen the videos I'd suggest watching them. The 'HDD Drive Install' is for replacing the HDD with either a new HDD or SSD. The 'SSD Installation' video is for adding an SSD without replacing the HDD or optical drive. https://eshop.macsales.com/installvideos/imac_21_mid_2011/

The 8GB of extra RAM has made a big difference, but am still tempted with the addition of say a 256GB SSD. I have watched the videos and it does look fairly difficult to do, although I would be willing to give it a go. Cost of internal versus external thunderbolt is about £80 versus £140. Does anyone out there think I could get an external thunderbolt SSD for under £100?
 
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Would a 128GB SSD be big enough as the boot drive for the OS?
If just a boot drive, then yes. My OS installs with basic software installs like Office and a few imaging editing applications etc. uses up around 30 GB.

But what is the price difference between the 128 and 256 GB? If not more than 40 pounds then I'd go with the 256.
 
If just a boot drive, then yes. My OS installs with basic software installs like Office and a few imaging editing applications etc. uses up around 30 GB.

But what is the price difference between the 128 and 256 GB? If not more than 40 pounds then I'd go with the 256.
Between £20 and £25. The option I am looking at is actually either a 240GB or 250GB versus a 120GB all from Crucial.
 
Was clearing out some iOS backups from the HDD last night and iMac really slowed down again during this. I opened activity monitor and pressure graph was red. Is this normal when deleting large files from the HDD? Would the addition of an SSD resolve this?
 
It was not normal for simply deleting a large file to slow the computer under HFS+, and I'd assume the same is true for APFS.

Secure deletions and deleting a large number of files can be a slow process due to increased disk activity, but I wouldn't have expected that to cause excessive RAM use either.

If the slowdown and red memory pressure happens again make a note of what process name(s) top the list for memory used.
 
I think he means the hard drive.

Have a look at this deal - seems pretty good. Macs Fan Control does what it says on the tin. Take you time and be careful and patient when doing the upgrade. GL :)
 
These are screen shots from failing hard drives. Notice that they all passed S.M.A.R.T. and Disk Utility showed them as good. TechTool Pro gives a different picture.

I had repaired each of these in Disk Utility before reformatting and sticking into a Time Machine dock connected eSATA. SMART tests cannot be run over ethernet or USB.

full.jpg


full.jpg


full.jpg


Unlike WD, Seagate at the time required some sort of proof before issuing an RMA for warranty. I stopped using Seagate when the replacement drives looked this bad after a month or two. Their quality is much, much better now.
 
These are screen shots from failing hard drives. Notice that they all passed S.M.A.R.T. and Disk Utility showed them as good. TechTool Pro gives a different picture.

I had repaired each of these in Disk Utility before reformatting and sticking into a Time Machine dock connected eSATA. SMART tests cannot be run over ethernet or USB.

full.jpg


full.jpg


full.jpg


Unlike WD, Seagate at the time required some sort of proof before issuing an RMA for warranty. I stopped using Seagate when the replacement drives looked this bad after a month or two. Their quality is much, much better now.
Thanks for the above, but this is getting too technical for me. Are you suggesting I use Tech Tool Pro to check my HDD?

Would an App like Clean my Mac X help with general housekeeping?
 
Last edited:
Are you suggesting I use Tech Tool Pro to check my HDD?
No. You've posted more than enough indicators. It's on its way out. It's old, tired, worn out. Replace it before it's an emergency.

The $99 cost of TTP can be spent for the labor to have it replaced with an SSD if you don't want to do the job yourself.
[doublepost=1540941338][/doublepost]
Would an App like Clean my Mac X help with general housekeeping?
No. The Mac OS is actually quite good at that — the opposite of what those utility companies would have you believe.
https://www.reddit.com/r/mac/commen...er_and_you_never_did/?st=jnwclcg9&sh=4c2d03ec

Save the money and fix your Mac.
 
No. You've posted more than enough indicators. It's on its way out. It's old, tired, worn out. Replace it before it's an emergency.

The $99 cost of TTP can be spent for the labor to have it replaced with an SSD if you don't want to do the job yourself.
[doublepost=1540941338][/doublepost]
No. The Mac OS is actually quite good at that — the opposite of what those utility companies would have you believe.
https://www.reddit.com/r/mac/commen...er_and_you_never_did/?st=jnwclcg9&sh=4c2d03ec

Save the money and fix your Mac.
Okay, so I was going to add an internal 240GB SSD and retain the original 1TB HDD, but looks like you are saying to completely replace the HDD. Am I correct? Budget will not allow for a 1TB SSD, so would you recommend replacing the 1TB HDD a new 1TB HDD and adding the 240GB SSD as the boot drive?
 
but looks like you are saying to completely replace the HDD
I've tried to be really clear on that point.

I understand that you're in the UK so I don't know what kind of prices you're looking at. You're asking about spending $99 for a test app and another $60 on a useless "cleaning" app. Although TTP is good, I service a lot of Macs and can justify the cost.

Let's take a look at what things cost: $159 is around £125.

You can get a 1T SSD for £59. It's a Micron 1100
https://www.amazon.co.uk/Docooler-I...e=UTF8&qid=1540948180&sr=8-19&keywords=1T+SSD

An 1100 is the same SSD as a Crucial MX300 (same company) but there's no warranty. It's an OEM and the VARS who use it in their products are expected to handle any customer service issue without sending it back to Micron/Crucial.

Don't buy an MX300 for £179 because there's better value. The MX500 has a 5 year warranty and costs £137, for example
https://www.amazon.co.uk/Crucial-MX...540948806&sr=8-25-spons&keywords=1T+SSD&psc=1

There are less expensive 1T SSDs like the Mushkin but I don't know what the warranty is. My recommendation for you is to go with the 1100. I have never had one go bad but I would get a commitment from the seller on some kind of return privilege in case of a defect.

Do you need the £9 bracket? Not really but it's highly recommended. You can attach it to the foil on the back with double-stick foam tape and people do. I don't.
https://www.amazon.co.uk/Sabrent-De...sr=8-5&keywords=2.5+to+3.5+hard+drive+adapter

The temp sensor on a 2011 iMac. The OWC is the ideal solution and looks like this. The included tape and pick are for the 2012–on but on AmazonUK, it's more expensive without them, oddly enough.
https://www.amazon.co.uk/OWC-OWCDID...ords=owc+in-line+digital+thermal+sensor+cable

Without the sensor, you have to control the fans manually. There are freeware apps that pop up a control panel. I tried that for awhile and hated it.

I know an inexpensive workaround for the 2009–2010 but not the 2011.
 
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I've tried to be really clear on that point.

I understand that you're in the UK so I don't know what kind of prices you're looking at. You're asking about spending $99 for a test app and another $60 on a useless "cleaning" app. Although TTP is good, I service a lot of Macs and can justify the cost.

Let's take a look at what things cost: $159 is around £125.

You can get a 1T SSD for £59. It's a Micron 1100
https://www.amazon.co.uk/Docooler-I...e=UTF8&qid=1540948180&sr=8-19&keywords=1T+SSD

An 1100 is the same SSD as a Crucial MX300 (same company) but there's no warranty. It's an OEM and the VARS who use it in their products are expected to handle any customer service issue without sending it back to Micron/Crucial.

Don't buy an MX300 for £179 because there's better value. The MX500 has a 5 year warranty and costs £137, for example
https://www.amazon.co.uk/Crucial-MX...540948806&sr=8-25-spons&keywords=1T+SSD&psc=1

There are less expensive 1T SSDs like the Mushkin but I don't know what the warranty is. My recommendation for you is to go with the 1100. I have never had one go bad but I would get a commitment from the seller on some kind of return privilege in case of a defect.

Do you need the £9 bracket? Not really but it's highly recommended. You can attach it to the foil on the back with double-stick foam tape and people do. I don't.
https://www.amazon.co.uk/Sabrent-De...sr=8-5&keywords=2.5+to+3.5+hard+drive+adapter

The temp sensor on a 2011 iMac. The OWC is the ideal solution and looks like this. The included tape and pick are for the 2012–on but on AmazonUK, it's more expensive without them, oddly enough.
https://www.amazon.co.uk/OWC-OWCDID...ords=owc+in-line+digital+thermal+sensor+cable

Without the sensor, you have to control the fans manually. There are freeware apps that pop up a control panel. I tried that for awhile and hated it.

I know an inexpensive workaround for the 2009–2010 but not the 2011.
Thanks for all of the above which is very helpful and clear what you are recommending. As I said before all this is new to me so had no idea about the cost of the apps when I asked the question. I have run disk utility and all seems okay with the HDD, although I know that you said in a previous post that this doesn't necessarily mean that the disk is healthy.

When I checked the Micron 1100 on Amazon UK, it looks like the £59 is for a 256GB HDD. The best price I can find for a 1TB HDD is around £140, which when you add the temp sensor cable at £40 and the bracket at £9 and an iFixit tool kit at £25 is over £210. I have already splashed out £55 for 8GB of RAM, therefore replacement of the HDD with an SSD of the same capacity is way over my budget.

My preference is to try adding a 240GB SSD (Crucial BX500 for £37, or MX500 for £47) plus the cost of the iFixit toolkit at £25 means I can do it all for £62 to £72. I would set up the SSD as the boot drive with the OS and Apps on it, but have my user folder on the HDD. Are you able to advise the best way of doing this. I have an external Seagate HDD that I use for Time Machine back-ups. Thanks again for all your assistance.
 
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