iMac's fan speed and GPU temp while playing ESO

Aenvar · July 2016

Hello all! I've been doing a lot of research on this topic recently but it's hard to get a clear answer so hopefully we can shed some light on the matter here. First of all please excuse my poor English, it's not my native language and it wasn't easy for me to explain (or rather try to) this kind of technical concepts on a forum post.

My iMac 5k will turn one year old soon so I figured it's about time to start taking good care of it

I create this thread because I'm interested in knowing other people's opinions on what is a reasonable GPU temperature (what I think it's the most heated component) & fan speed while playing this wonderful game. It also might help other mac owners who had no idea about this stuff like I didn't one year ago!

I never had checked this stuff at all because these computers are very silent & it's expected for them to get quite hot during heavy use like gaming... But after downloading the Macs Fan Control app I realised that maybe it gets too hot (80-90 Celsius, 95-100 in big fights like Cyrodiil) for its long term safety. I haven't had the chance to ask an apple expert yet but on the internet opinions seem very mixed. Some think that the computer is perfectly fine anywhere below 100 Celsius (when by standard the comp will slow itself down to prevent possible damage) because the iMac is built like a laptop - known to have less space for ventilation so the components are made to endure higher temperatures (the aluminium case also helps as a heat conductor). Others say that no matter what it's not good for any device to get past 80 - 90 Celsius for too long at the risk of reducing its lifespan.

So I adjusted the fan to move faster and keep the GPU cooler. Right now ESO runs mostly between 70 and 80 C (never above 85 but that's quite rare, only happens once or twice per session), and the fan speed goes between 1500 and 2000 RPM (still very silent!), up to 2300 very occasionally during some cyrodiil or boss fights. My settings are all at High besides shadows, turned down to Medium because I don't notice them too much. Resolution is set to 2560 x 1440.

What do you think? Do you think it's bad to use these apps to accelerate the fan speed? How hot does your machine run and how risky do you think it is? What do you consider a "dangerous" temperature for the GPU / fan speed?

Thank you very much for your time & see you in Tamriel!

Nestor · July 2016

Aenvar wrote: »

My iMac 5k will turn one year old soon so I figured it's about time to start taking good care of it

Excessive heat can reduce the life of your PC, so it's good your looking into this.

Your computer is like a vacuum cleaner for all the dust in your house. It gets sucked in and coats the fans and heat sinks. Over time, this will cause your machine to run hotter and hotter, to the point it might shut down for thermal protection.

I am not sure how hard it is to pop the case side off, but if you can, it will make the next step easier. Get a can of compressed air (office supply place, home improvement center or similar sell this, or online). Take the machine outside, you don't want to do this in your house, and blow out the dust from the fans and heatsinks. Be careful with the fans, too much force from the air can damage the bearings and you have to replace them.

As for temps, it can very as to what is safe. I had a video card that would not go into thermal shutdown until it hit 100 degrees C, basically boiling water. Most people agree that 50 to 60 degrees C under load on a video card is a good target to keep things happy inside your computer.

I use an app to control my fans as I would prefer the system to be as quiet as possible unless I am in a full on frag fest in a game, where I can't here the fans anyway. So I set up custom curves to lower the fan speeds at low temps, and crank them up at higher temps. You can use a Benchmarking Program to load up the video card (3D Mark used to have a free demo you could use) and that can help you set the fans to the speeds you want and need for temp control and silence.

But, do blow out the dust and furballs from inside your machine, that is the first step. You can also get something like this for your system to help with cooling if you feel the need

https://www.amazon.com/iHome-Mac-Cooling-Pad-IMAC-A300S/dp/B007X3VEUC

Macs are a bit different, so get one designed for your specific system.

smacx250 · July 2016

Well, I've spent my career in the semiconductor (CMOS) industry, and high temperature, regardless if the component is designed to operate at that temp, will reduce the component lifetime. Will it reduce it enough that it will fail for you - can't say (it is a statistical failure rate, looking at how many fail over a large number of units). However, fans generally fail more often than the chips, and they fail based on how many times they spin, so spinning your fan faster will lead to a shorter fan life. That said, fans are generally easier to replace than chips (not soldered on), so I'd take a fan failure over a chip failure - given the fan failure doesn't go unnoticed and seriously cook the machine!

100C is a typical design point for commercial silicon these days, though 125C isn't terribly uncommon - but harder to design to because static power goes up and speed goes down as operating temp goes up (yes, the hotter it gets the more power it uses, so it gets even hotter - cooling needs to be designed to prevent thermal run-away). I can't say what your GPU was designed to, but I'd guess if you see it at 100C and the fans aren't running full speed, it is designed for at least 115C or 125C.

My personal advice would be to leave things as is - the engineers that designed the machine know the allowed operating temperatures of the various components, and presumably have designed the cooling system to achieve a good tradeoff between keeping the system within operating limits, maximizing both silicon and fan life, and keeping noise levels reasonable. This isn't a white-box PC thrown together out of random components - it is a closed system all designed by a reputable company. In saying this, I'm assuming you haven't made any modifications to the machine.

KhajitFurTrader · July 2016

As @smacx250 said, a Mac's CPU running at 70-90 C for prolonged times is quite normal, and I see it all the time while playing. Even temperatures over a 100 C for shorter periods are OK, as the thermal budget of both CPU and system allows for them. Before any physical harm comes to the CPU, thermal throttling would set in.

Be careful when using third party software that tampers with hardware parameters like fan speeds. Macs are finely tuned systems, every component is geared to each other. You use this software at your own risk, and using it might inadvertently shorten the machine's lifetime if wrong parameters are chosen.

Aenvar · July 2016

smacx250 wrote: »

I can't say what your GPU was designed to, but I'd guess if you see it at 100C and the fans aren't running full speed, it is designed for at least 115C or 125C.

Yes, this is a very important point and I completely forgot to mention it. Even before the adjusting, when getting to 90 celsius was far more common than now, the iMac's fan speed didn't ramp up until it got to the 95-100 range (and for a very short period I must say).

Thank you very much for all the answers and information so far, it's really valuable for us computer newbies

Slammer99uk · July 2016

Same machine here as OP's and I would heartily recommend a little known app called TG Pro:-
https://tunabellysoftware.com/tgpro/

Not only does it allow you to monitor temps and fan speeds for just about every sensor you have, but it will allow you to create temperature/fan profiles that really do work well.

Ok it's not free ($16) but it works and works very well. Updated constantly to keep up with newer Macs with added/different sensors from older Macs.

At least check the tutorial out to see what it can do:-
https://tunabellysoftware.com/support/tgpro_tutorial/

I do not work for the publisher, I am just impressed with the functions and support.