iMac 2017 HDD Thermal Sensor

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iMac Intel 27" Retina 5K Display (Late 2014 & 2015)

Model A1419 / EMC 2806 / Late 2014 or Mid 2015. 3.3 or 3.5 GHz Core i5 or 4.0 GHz Core i7 (ID iMac15,1); EMC 2834 late 2015 / 3.3 or 3.5 GHz Core i5 or 4.0 GHz Core i7 (iMac17,1) All with Retina 5K displays

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Dan @speedglas

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发帖于: 2020年2月2日

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iMac 2017 HDD Thermal Sensor

Brauche Ich wenn ich die SATA Festplatte ersetze einen Temperatursensor damit der Lüfter nicht hoch dreht? Imac 27” Mid 2017 3,5Ghz I5

Do I need a Temperature Sensor if i replace the Sata HDD with a Sata SSD in my Imac 27” Mid 2017 3,5Ghz I5? Will the Fan run on Max if there is no Sensor?

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DanJ @danj

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Apple änderte leise seine Firmware, um die Notwendigkeit des Inline-Sensors ab den Modellen von 2014 zu beseitigen. Wir wissen nicht genau, warum oder welche SMC-Firmware diese Korrektur hat, sie ist möglicherweise nicht permanent.

Dies könnte damit zusammenhängen, dass die Festplattenanbieter nicht gezwungen werden sollen, ihre Laufwerke zu ändern. Oder die neueren SMART-Definitionen haben den Grund behoben, da die ältere Spezifikation einen Hardware-IRQ zum Lesen benötigt, der das System verlangsamt, wenn Sie dies sehr häufig tun.

Apple quietly altered their firmware removing the need of the in-line sensor starting in the 2014 models. We don’t know the details on why or which SMC firmware has this correction, it might not be permanent.

it could be related to not wanting to force their HDD suppliers to alter their drives. Or the newer SMART definitions resolved the reason, as the older spec required a hardware IRQ to read which slows the system if you are doing it very frequently.

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Thanks for your quick response. So if i want to do it properly it would be better to buy a Sensor also for the 2017 Model?

由 Dan 完成的 2020年2月2日

I've ben going without adding it, as why add an additional cost to the customer needlessly.

I do tell them to keep an eye on the thermals using a good app like TG Pro and if after a OS update the system acts up to see me. So far so good!

由 DanJ 完成的 2020年2月2日

So the fan doesn't speed up to 2000Rpm in System Automatic mode?

由 Dan 完成的 2020年2月2日

I'm not I follow your logic here??

The fans speed is controlled by SMC. It depends on thermal sensors throughout your system. As far as the HDD (or if you've replaced it with a SSD) Apple had been using a custom HDD which offered out the HD's internal thermal sensor via the HD's SATA connecter pins as a direct feed for SMC. All of the HD vendors have embraced SMART years ago.

It had a large issue, the way it works is via an IRQ Request while polling SMART every so often (i.e. hourly). But what happens when you are doing this every second or even more! Apple couldn't use SMART in the older version which is why it did what it did!

But a few years ago the ATA standards body did tighten down some of the looseness within SMART spec and Apple did apply an addendum to the standard (I haven't seen the latest version of the spec so I can't tell you if it was accepted or not). If it was or if Apple got the HD vendors to apply the update to their drives that could explain things.

So I would stick with a currently produced drive Vs using an older model that is older than two years.

由 DanJ 完成的 2020年2月2日

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Thanks for your quick response. So if i want to do it properly it would be better to buy a Sensor also for the 2017 Model? — Dan
I've ben going without adding it, as why add an additional cost to the customer needlessly.

I do tell them to keep an eye on the thermals using a good app like TG Pro and if after a OS update the system acts up to see me. So far so good! — DanJ
So the fan doesn't speed up to 2000Rpm in System Automatic mode? — Dan
I'm not I follow your logic here??

The fans speed is controlled by SMC. It depends on thermal sensors throughout your system. As far as the HDD (or if you've replaced it with a SSD) Apple had been using a custom HDD which offered out the HD's internal thermal sensor via the HD's SATA connecter pins as a direct feed for SMC. All of the HD vendors have embraced SMART years ago.

It had a large issue, the way it works is via an IRQ Request while polling SMART every so often (i.e. hourly). But what happens when you are doing this every second or even more! Apple couldn't use SMART in the older version which is why it did what it did!

But a few years ago the ATA standards body did tighten down some of the looseness within SMART spec and Apple did apply an addendum to the standard (I haven't seen the latest version of the spec so I can't tell you if it was accepted or not). If it was or if Apple got the HD vendors to apply the update to their drives that could explain things.

So I would stick with a currently produced drive Vs using an older model that is older than two years. — DanJ

iMac Intel 27" Retina 5K Display (Late 2014 & 2015)

iMac 2017 HDD Thermal Sensor

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