Crucial MX500 Upgrade on iMac 2013 27"

Kilobyte Kid

Re: Crucial MX500 Upgrade on iMac 2013 27"

Here's a grab of the Activity Monitor CPU with no applications open:

 

Screen Shot 2018-07-18 at 17.51.42.jpg

 

 

 

JEDEC Jedi

Re: Crucial MX500 Upgrade on iMac 2013 27"

Is the iMac the all-in-one system?  I have a vague recollection that those old all-in-one systems had some proprietary way of measuring the drive temperature that meant using a third party drive would cause the fans to always run flat out as they couldn't detect the drive temperature.

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JEDEC Jedi

Re: Crucial MX500 Upgrade on iMac 2013 27"

 

@sckennedy   

When you tested performance by booting to an external USB3 drive, did you turn off Spotlight for both drives?  Also were you using a SATA III hard drive and does your USB adapter/dock/enclosure support UASP?   If so, booting from a USB3 SATA III hard drive should perform fairly close to an internally installed hard drive, but it does depend on the USB adapter/dock/enclosure being used.  If so, then I would suspect the missing temperature sensor may be causing your issues.  I don't recall seeing a performance issue on older 2010/11 iMacs, but it has been a while since I worked on one without a sensor and I wasn't using Sierra/HS either.  Without the drive temperature sensor, the iMac will run the fan at high speed as a safety precaution.    See my earlier post on where to purchase a temperature sensor adapter.

 

You mentioned you checked the SMART status in an earlier post, but it might be useful to post a screenshot of the actual SMART attributes as the apps don't always provide alerts for some errors and it might tell us if the SATA cable could be at fault.

 

 

Did you check the disk activity with Activity monitor as I suggested in a previous post?  If so what were the transfer rates and were they sustained during periods of slowness?

@HWTech wrote:

 

Open Activity Monitor located in the Utilities folder and select the Disks tab and check on the disk activity in the lower right (Data read/sec   & Data written/sec).   If this number is constantly in the MB range, then try to determine what is reading or writing to the SSD.  (Spotlight, macOS updates, Anti-Virus scan, Filevaulting etc.)

 It might be worth trying an SMC reset and a PRAM reset (newer Apple systems no longer chime or show video on the screen during a reset, so hold the PRAM reset for a minute just to be sure it reset at least three times.  If you look closely at the LCD you may be able to notice very subtle changes as the backlight turns on & off during each reset.  I've seen some issues needing the three chimes/resets).

 

I was recently testing an MX500 SSD and also saw the slow 250MB/s transfer rates when I ran tests using both OSX & Linux.  I discovered Linux was partitioning the SSD beginning on a 2K block instead of a 4K block.  After making this change the SSD performed at 450MB/s.  Unfortunately I never double checked how OSX had partitioned the drive, but I'm guessing it was the same way.  I'll see if I can try a quick check on this tomorrow and report back.   I never saw the max speed as low on the earlier MX300 series using the same partitioning tools, but the MX500 is using a different controller than the MX300 series.

Kilobyte Kid

Re: Crucial MX500 Upgrade on iMac 2013 27"

Hi HWTech,

"When you tested performance by booting to an external USB3 drive, did you turn off Spotlight for both drives?" - No, I will try.

I used a regular flash drive connected via a USB3 cable.

Booting from an external drive - can this test indicate whether the SSD/temperature sensor is faulty?

When the new SSD was installed the original SATA cable was used - bad move?

SSD is formatted APFS with High Sierra.

 

SMART screenshot:Screen Shot 2018-07-19 at 10.31.37.jpg

 

 

Activity Monitor screenshot:Screen Shot 2018-07-19 at 11.12.40.jpg

 

 

Attempted SMC and PRAM resets with no improvements.

Please note that TRIM is still enabled - is that OK?

Many thanks for all your assistance.

Simon

JEDEC Jedi

Re: Crucial MX500 Upgrade on iMac 2013 27"

 wrote:

Hi HWTech,

"When you tested performance by booting to an external USB3 drive, did you turn off Spotlight for both drives?" - No, I will try.

I used a regular flash drive connected via a USB3 cable.

If you used a USB stick/pen drive then that is why the external booting was so bad.  USB sticks are very slow when used to boot an installed OS as the OS is writing to the stick and most USB sticks have absolutely abysmal write speeds.   If instead this was an SSD then that is a different matter and may be a concern.

 

 

 

Booting from an external drive - can this test indicate whether the SSD/temperature sensor is faulty?

The SSD does have an internal temperature sensor which the SMART attributes will show you, but it is not being used or monitored by the iMac AFAIK although I've never actually worked on your particular model to know for certain.  The fan running at high speed is the usual indicator though, unless of course another sensor/cable was damaged or left disconnected.   On 2010+ iMacs Apple uses custom firmware on their Apple drives and only those drives report the temperature properly to the system.   A third party inline adapter for the SATA cable is available which includes a compatible temperature sensor.

 

 

When the new SSD was installed the original SATA cable was used - bad move?

SSD is formatted APFS with High Sierra.

Please note that TRIM is still enabled - is that OK?

 

I would hope the SATA cable would be Ok on such a recent model, but you never know.   On some systems the SATA cable is not easily replaced.  The SMART attributes don't show any problem with the cable.

 

Since APFS is a brand new filesystem, it may have undiscovered issues especially with untested non-Apple drives.  It can take a while to perfect a filesystem.   Is the drive FileVaulted or using APFS encryption?  Check even if you did not enable it as I heard Apple might be planning on enabling it by default at least on their laptops.   

 

As far as TRIM support I know that the Debian Linux distribution automatically disables TRIM on certain SSDs during the OS install due to known issues with certain SSDs.   While TRIM support is nice, I've also read several places where people have made convincing arguments against using TRIM.  Personally I'm torn on its use since historically Apple has gone out of their way to disable support on non-Apple SSDs.   As long as you allow your SSD to rest without a lot of disk I/O the internal Active Garbage Collection will do its job during the quiet periods.

 

In the Energy Saver Preferences disable "Put drive to sleep when possible".   I've seen a lot of reports where enabling power management on an SSD causes problems.   SSDs don't use that much power anyway.   You may want to disable Power Nap as well at least while testing things.

 

The SMART attributes look Ok except for the SSD's internal temperature.   It appears the SSD was at 70°C at some point which is about when the SSD will begin to throttle its speed which will impact performance.  From your screenshot the current temp of your SSD is 30°C which is fine.   Either your iMac was running a bit hot or the SSD is actually being used quite heavily to get the SSDs temperature to this point.   Monitor the Disk I/O for the SSD during times when you get the slowdowns to confirm if it might be due to execessive data transfers with the SSD.    What temps does Macs Fan Control report for your CPU, SSD and iMac enclosure temps during normal periods and during the slow down periods?   If the enclosure temp is low but the SSD temp is high then it is probably due to excessive SSD activity.   If the enclosure temp is running near the SSD's temp, then most likely the iMac is causing/contributing to the SSD's higher temperature.   The CPU temps probabably should not go above 100°C (at least it doesn't on the current MBPros when I run mprime stress test).

 

You should try running the Apple Hardware Diagnostic to see if it reports any failures besides the drive temperature sensor.   There is a chance it may complain about the Crucial SSD, but it should be safe to ignore as some Apple diagnostics will complain about third party drives and others diagnostics let it pass).

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Kilobyte Kid

Re: Crucial MX500 Upgrade on iMac 2013 27"

Hi HWTech,

I'm biting the bullet and removing the screen again.

I've purchased an OWC Thermal Sensor Kit.

I'll pull the SSD drive and will test thoroughly before installing the sensor.

Incidentally I ran the Apple Diagnostics Test resulting in a reference code of PFM006 - SMC error.

I've reset the SMC wiith no joy.

Any top tips on further diagnostics once the screen is removed?

Many thanks,

Simon

JEDEC Jedi

Re: Crucial MX500 Upgrade on iMac 2013 27"

I've never worked on a 2013 iMac so my specific knowledge for this model is limited.   When you remove the LCD, put it aside leaning it upright making sure it won't slide or fall.  If you put it flat it could crack under its own weight (I've seen this happen with a 27" LCD).   Double check all cables are secure.   With older iMacs it is easy to not get them seated properly during the reinstall or even miss one.  You may want to look around at other cables you didn't touch in case something accidentally got loose.

 

If you have problems let me know and I can look at the Service Guide for you.

Kilobyte Kid

Re: Crucial MX500 Upgrade on iMac 2013 27"

Hi Simon

 

I have exactly the same problem as you and think I have found the solution 10 minutes ago. It was when I noticed you had broken your screeb that th epenny dropped. I too added the MX500. It worked fine for a week with the screen unglued. Then I glued it up (using the iFixit sticky ribbons) and one of the connectors must have come loose. I then broke the screen when opening it. Yesterday i fitted the new screen and it runs like a dog - just as you described. 

 

Read this article for the solution - its the temp sensor on the new screen causing your mac to boot in safe mode. I havent openedmy mac yet but I did keep the broken one. TG Pro (licensed version $18 I am afarid) will confirm the problem.

 

Good luck

Kilobyte Kid

Re: Crucial MX500 Upgrade on iMac 2013 27"

Kilobyte Kid

Re: Crucial MX500 Upgrade on iMac 2013 27"

Hi Simon

 

Just opened up the iMac (without breaking  the screen this time!) and sure enough, no temp sensor on the new screen. This was causing it to boot up in safe mode with fan on full. If you have junked your old screen you can buy a new temp sensor.

 

https://www.ifixit.com/Answers/View/458981/How+to+detach+LCD+thermal+sensor+cable

 

Good luck