3D rendering and CPU temperatures

[Kryten]

Guys, just lately I've been doing quite a bit of 3D rendering, which when you start the render process the CPU's get pretty hot. Normally a render takes between 25 to 60 minutes. Is it safe to do this or could it damage the CPU's?

 

[pigoo3]

I believe you have a 2020 model iMac...thus the high temps are not due to having an older computer...and asking it to do too much.

3D rendering is one of the most resource intensive things you can ask a computer to do. Generally the rendering will take advantage of all CPU resources available to it.

Apple computers are designed to shut down if they get too hot.

Is it possible the room the computer is in is on the hotter side (no air conditioning)? Ambient room temps will definitely increase computer temps. I'm guessing during the cooler months (Winter)...your iMac doing the same rendering would run cooler.

- Nick

 

[Kryten]

Thank you Nick. You've put my mind at rest. You have an amazing memory, yes I have a 27" 2020 iMac i7, 80gb memory, 8 cores etc.... I'm in the UK where generally we don't have air con on our houses, British weather usually doesn't require it... It's not particularly hot here at the moment anyway.
I would presume whichever Mac I buy will have similar heat issues when rendering?

 

[pigoo3]

Thank you Nick. You've put my mind at rest. You have an amazing memory, yes I have a 27" 2020 iMac i7, 80gb memory, 8 cores etc.... I'm in the UK where generally we don't have air con on our houses, British weather usually doesn't require it... It's not particularly hot here at the moment anyway.

I've been reading stories about how historically hot it has been in the UK this year...and how air-conditioning is not something most folks need or have had traditionally in the UK. Thus wasn't sure if ambient home temps could be an issue with your iMac.

If you say all is good from this perspective...good deal.

I would presume whichever Mac I buy will have similar heat issues when rendering?

You didn't mention wanting to buy anything...especially since this iMac is only about 2 years old. But if you needed something with more/faster performance (shorter rending times)...buying something newer is always a possibility.

I've done quite a bit of research myself...looking into the newer Apple Silicon Mac's. One of the tests many reviewers do is rendering to help quantify how powerful an Apple silicon Mac is compared to older Mac's (previous year models for example). In many cases an Apple Silicon Mac vs. an Intel based Mac of the same model type is tested (iMac vs, iMac, MacBook Pro vs. MacBook Pro, etc.).

Of course one of the tests many reviewers will do is compare rendering times (usually the newer Apple Silicon Mac win's/is faster)...but other info they communicate is fan noise & computer temps (since as you've experienced...when rendering fan noise & computer temps are higher).

In almost every review I've seen (newer Apple Silicon Mac vs. older Intel Mac)...when these guys do a rendering test/comparison...the Apple Silicon Mac's generally run much quieter & much cooler...while at the same time being faster & using less energy (watts).

If you were considering purchasing something newer...definitely go with an Apple silicon Mac. So many positives compared to older Intel based Mac's (faster, cooler, quieter, less energy, etc.).

HTH,

Nick

 

[Randy B. Singer]

Guys, just lately I've been doing quite a bit of 3D rendering, which when you start the render process the CPU's get pretty hot. Normally a render takes between 25 to 60 minutes. Is it safe to do this or could it damage the CPU's?

Heat is the natural enemy of magnetic media (your Mac's storage) and extreme hot and cold cycling causes metal to expand and contract. Enough expansion and contraction of the soldered joints of individual components will cause them to crack and fail (i.e. it will cause a "cold solder joint"). So it's definitely a good idea to keep things on the cooler side as much as possible.

I was told by someone that I know at Apple that Apple is sensitive to the complaints of users who say that fan noise is bothersome. So Apple has set their fans to come on later than they might, and when they do come on they tend to be less aggressive than they might be.

You can fix this with a free utility. You can set your fans to come on earlier, and run at a higher speed.

Here is a utility that makes it easy to keep track of the temperature of your internal components, and the speed of your fans:

Fanny (free)
https://www.fannywidget.com/

Here is a utility that will give you the ability to set when your fans come on and how fast they run:

Macs Fan Control (free)
https://crystalidea.com/macs-fan-control/download

 

[Raz0rEdge]

What's important is that the temps rise, the fan speeds should rise as well to ensure that the heat is being dissipated. If the building heat of the CPU doesn't dissipate, that's when you'll get thermal shutdowns.

The innards of the computer has micro climates, so as the CPU is handling intensive tasks, it gets hot and the immediate area does as well, but there's a heatsink on it to send that heat elsewhere so no risk of the rest of the system being affected by it.

Ambient temps will determine what the temps inside the machine are.

It's vital to ensure that you keep the airflow channels clear for the iMac's cooling system to do its job.

On the iMac, the intake vents are at the bottom of the screen (where the RAM is installed) and the air is sent over all the components and out the top-back of the screen. If you put your hands on the top, it should be warm.

Unlike mechanical parts, a CPU repeatedly heating and cooling doesn't cause any damage to it. The Intel chips will operate upwards of 120C without any issues. The Mx-based Macs in contrast will not get as hot while performing the same actions.

 

[Kryten]

Gentlemen, apologies for late reply but the notification went straight into spam on the server. Only just spotted it checking via webmail.
Thanks very much for the excellent advice and suggestions. I hadn't planned to buy a new Mac as this is, as Nick says, only 2 years old. I spent £8 GBP on TGPro which is pretty good for temperature info. Most of the time while rendering everything is okay but only once did the iMac become completely unresponsive, strangely whilst not rendering but shortly after. Anyway everything seems to be running fine now, so thanks again for your valuable input. Over and out.