Fan on high with SSD Nvme upgrade

[psymac]

Just installed the Samsung 970 Evo 1TB Nvme blade in my 2017 27" iMac (it was a 2TB Fusion). Now when I run Blackmagic Speed Test the internal fan starts up and goes to high speed, did not do when I installed a 500GB Evo a couple of weeks ago. Is this normal or did I get a bad 1TB SSD? For normal everyday use the fan does not come on so far.

 

[jerwin]

Do you have a program that can read the temperature sensors?

 

[psymac]

Do you have a program that can read the temperature sensors?

Yes, CPU stays around 50 degrees (C) and the SSD at also 50 at idle with fan at 1200rpm, but under Black Magic test mode SSD goes quickly up to 70 and fan at 2000rpm.

 

[jerwin]

I don't have the same imac as you do, but on my machine, iStat Menus breaks down the various temperature sensors like so:

note the HD and SSD readings. I'm thinking that your imac reads an anomalously high temperature from your now missing HDD

 

[mikehalloran]

"Doctor, it hurts when I do this"

"Don't do that"

Seriously, you removed the HDD and didn't replace it. It had a built in temp sensor that is now missing. To make the issue go away, install the OWC temp sensor. It doesn't have to attach to anything else.

OTOH, if that test is the only thing causing the fans to peg, stop running the damned test—it's looking for something that isn't there and freaking out when it's not found.

 

[mikzn]

Yes, CPU stays around 50 degrees (C) and the SSD at also 50 at idle with fan at 1200rpm, but under Black Magic test mode SSD goes quickly up to 70 and fan at 2000rpm.

that's kind of normal - BlackMagic is performing various tests and some are video tests and designed to test the CPU under different loads - you can't have superior CPU processing without more heat - IMHO 70 degrees doesn't seem excessive for high end video conversion type tasks and it probably gets throttled after that.

I have a Samsung 970 pro in my rMBP 2015 / i7 processors - should be more sensitive to heat - it does not overheat or go above 50 degrees (C) unless I use the rMBP to convert video from one format to another or some other CPU intensive task.

Is the only concern the Black Magic Test? If so I would not be that concerned.

 

[psymac]

"Doctor, it hurts when I do this"

"Don't do that"

Seriously, you removed the HDD and didn't replace it. It had a built in temp sensor that is now missing. To make the issue go away, install the OWC temp sensor. It doesn't have to attach to anything else.

OTOH, if that test is the only thing causing the fans to peg, stop running the damned test—it's looking for something that isn't there and freaking out when it's not found.

Why would a temp sensor on the HDD affect the SSD?

Did not see this temperature rise with the 500GB 970 EVO I had installed a couple of weeks before, same configuration - no HDD but cable still in place. No HDD's are in the stock 500GB or 1TB Apple OEM iMacs, so should not be an issue here, but I will try both adding back the HDD and then removing both the HDD and its cable.

Otherwise, I don't think I can recommend the 1TB Samsung EVO 970 for at least the 2017 27" 3.8ghz iMac. The 1TB EVO has exactly the same form factor as the 500GB, so thermally may be at its limit.

 

[Plan-B]

(it was a 2TB Fusion)

No HDD's are in the stock 500GB or 1TB Apple OEM iMacs

Not sure what these two statements are communicating, but if you had a Fusion drive, by definition you had a spinning HDD. The "Fusion" marries an SSD with a platter-based drive.

Also: "Why would a temp sensor on the HDD affect the SSD?"

It doesn't. The temp sensor in the factory HDDs affect how and when the fan operates (along with all the other temp sensors Apple installs). If you yanked the spinning HDD part of the Fusion drive, you also removed a factory temp sensor. When iMacs detect this sensor missing, they have a tendency to max out the fan speed because it doesn't know if the sensor just failed, you're running max temps, or whatever is in between. So it defaults to full throttle. This has been the behavior of iMacs for many, many generations. What people are saying is that if that HDD sensor is somehow missing, you need to put in the OWC sensor so that the OS can read a valid temp when it looks for it and run the fan at the correct speed.

 

[psymac]

Found this high temperature (>70C) and subsequent speed throttling (<1400 R/W) within two minutes of speed test, with or without HDD installed, and also found it now for both the 500GB and 1TB 970 EVO SSD.

Although it may not affect routine functionality, it does seem unusual and perhaps a concern for those with need for high R/W throughput.

Others with a stock 500GB or 1TB SSD iMac (which came without a HD) could also run a Blackmagic Disk speed test, and at the moment doubt they would see the same quick SSD heating and subsequent throttling.