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Question: iMac Pro 8 Core Warm to Touch While Sleeping Fans High After Wake

This morning when I hit the power button to wake my iMac Pro from sleep, the chassis was a bit warm to the touch. Within a minute of waking from sleep and unlocking with Apple Watch, I heard the fans on high. I recently built 1:1 previews for >2000 raw files and never heard the fans. Touching the chassis in various locations around back the chassis wasn't "hot" but I suspect it was warmer than it would ever get in a full day of actual use. And there was columns of warm air blasting from the exhaust port with the fans spinning on high (has anyone heard their fans spool up to high?). I looked at activity monitor right away and of course cpu utilization was low/normal.

I wonder what was generating this heat while it was asleep? This causes me a bit of concern to know something is getting hot inside while asleep without active cooling available. I'll be shutting down in the future overnights and when no one is home.

Base iMac Pro [8 core 32GB 1TB Vega 56. macOS 10.13.3] 8TB Lacie TB3 drive plugged into TB3.

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Mar 16, 2018 5:46 PM in response to jbhmacpro In response to jbhmacpro

I've never had that happen in the going on three months I've owned mine. I can only suggest disabling "Power Nap", "Wake for network access" and "Put hard disks to sleep…" in System Preferences > Energy Settings and test.

You could also test in a new account.

How to test an issue in another user account on your Mac - Apple Support

Mar 16, 2018 5:46 PM

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Mar 17, 2018 6:23 PM in response to jbhmacpro In response to jbhmacpro

I noticed this on my replacement iMac Pro...my first one had a problem with panic attacks and restarting...my replacement runs fine but after 2weeks noticed that once awakened sometimes the fan would blow for a short period. using istat the temperature would rise overnight in sleep...I could track this consistently....and once awake and even heavy use it would cool down (the cooling system worked)...to kinda solve this issue I had to check "prevent this computer from sleeping automatically when the display is off".....I think in sleep the fans shut off but the work class components are generating heat.

Mar 17, 2018 6:23 PM

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Mar 17, 2018 8:10 PM in response to MFASM In response to MFASM

I looked at Console and at 2:40 a.m. two apps did get updates. It was approximately 9 a.m. when I woke up the iMac from sleep and finding it warm.

Regardless, I have turned off power nap. and will not allow the iMac Pro to sleep for extended periods choosing instead to shutdown. It frightens me to think all those pricey components are getting hot inside without the aid of active cooling. I'll just choose shutdown like it's 2005 until a level of trust returns.

This was the first time that I had heard the fans. The fans spun up for about 3 minutes before they returned to their usual state. Besides this hiccup I have been massively happy with my $5k expenditure.

Mar 17, 2018 8:10 PM

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Mar 19, 2018 9:47 PM in response to jbhmacpro In response to jbhmacpro

Just got my iMacPro a few days ago. Today I noticed that when coming out of sleep the fans will roar for about a minute and then go back to normal. Power nap is turned off.

It it didn’t do this the other day when I was testing if coming out of sleep would cause any issues with attached hard drives.

I also have the crypto error others are reporting here when running disk utility. But otherwis all is fine

Mar 19, 2018 9:47 PM

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Apr 5, 2018 1:47 AM in response to Jadeviper In response to Jadeviper

I have had the problem, too (standard iMac Pro with 10.13.4). I switched off power nap and it did not occurs again. But it should work even with power nap enabled ... !!! My MacBook Pro is able to run with power nap enabled without heating the room.

I also have the crypto error problem. Regarding the later problem, I talked with the apple support, gave them system diagnostics and so on. Two days later they told me that this problem is not severe and that they are working hard to solve it.

Apr 5, 2018 1:47 AM

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Question: iMac Pro 8 Core Warm to Touch While Sleeping Fans High After Wake