MBP 15'' 2018 (specially i9): Do the fans kick-in for single-core tasks?

[asiga]

Hi,

I'm reading a lot about the new MBPs being very loud, but I'd like to have some comparison to what I already know, which is the MBA:

I'm used to the MBA fans behaviour: When doing single-core tasks (100% CPU load), the fans never kick-in (except perhaps if you are in a very hot room, or if the iGPU is also working, but, in normal conditions the fans are idle at single-core 100% CPU load).

If you run a double-core task (CPU load higher than 100%), then the fans kick-in (and they are quite noticeable).

I'm considering the i9 MBP (yes, I know it's thermal-limited, but I usually perform single-core tasks, and the i9 has got a noticeable higher geekbench mark than i7 for single-core), and I'd like to know if I'm going to experience a radical change in noise from my MBA for single-core only. So, my questions would be:

- Do the fans kick-in when the MBP 2018 is at 100% single-core CPU load? (specially the i9, but I'd also like to hear about the i7).

- Are the fans much louder on the MBP 2018 than on the MBA? (when they are at full speed, I mean).

Thanks!

 

[leman]

It depends on how long it runs. If only its 20 seconds, the fans are inaudible. If its longer, then yes, it will get loud. Power draw of CPU in single threaded loads can exceed 30Watts, and it does take some cooling to deal with it (compare it to "average operation" where the CPU (draws 3-5Watts). The fans work on on-demand basis and kick in when the temperature increase exceeds certain threshold.

 

[grillface]

Hi,



- Do the fans kick-in when the MBP 2018 is at 100% single-core CPU load? (specially the i9, but I'd also like to hear about the i7).

- Are the fans much louder on the MBP 2018 than on the MBA? (when they are at full speed, I mean).

Thanks!

It's funny you ask this because I am undertaking your exact scenario as we speak.

I have an i7/2.6 GHz. Right now I am in Boot Camp and running an environmental simulation which is single-core only. Windows Task Manager shows the CPU running at ~4.2 GHz and the fans are indeed audible. They ramp up and down as the simulation progresses. I don't know about the Air, but it's definitely quieter than my 2011 15" at full bore! Actually I am pleased at how quiet it is running, to be honest, but that is subjective.

 

[asiga]

Thanks a lot for your replies. Actually, what I would want is a 15'' MacBook (not Pro) without fans, but 1) That MacBook doesn't exist, and it's unlikely to be introduced this year, and 2) I've just got imminent need for big virtual machines that make me want to have 32GB RAM.

So, no matter how you look at it, it's unlikely to see a 32GB RAM 15'' fan-less MacBook in the short term, and the only option is the MBP.

I'm ordering one, and I have the intuition that it's not going to be as noisy as some people claim (specially because my multi-core usage is limited -just spare calculations that take 10 minutes or so-, most of my work is single-core).

Thanks for all your replies!

 

[Lennyvalentin]

I'm reading a lot about the new MBPs being very loud

"Very loud" is relative. Coming from a 2011 13" MBP with its single fan, the dual fans in my 2018 13" MBP are WAYYY quieter. Even at full bore they're so much quieter, it's a huge difference. Most of the time, my macbook doesn't make much sound at all. Also, 15" MBP have larger diameter fans which will produce a slightly lower tone of fan noise which the human ear will have an easier time coping with. So I wouldn't worry so much, honestly.

 

[buran-energia]

Disabling turbo boost should help a lot with your concern. But on 15 the fans never turn off unlike on 13 or air. In a quiet envinronment with good hearing you will hear them slightly, but this is not a problem for most. That's on top of SSD coil whine that some seem to suffer during reads (?).

Btw, on air and on 13, it's possible that the fan(s) spin, but are inaudible. You need check with istat menus, as I doubt your air doesn't turn it on during 100% 1 core usage.

 

[asiga]

I ordered a 15’’ i9/32GB/1TB/silver yesterday, because after a lot of thinking that’s what I’ll need for the coming years. I would have preferred a fanless 15’’ MB, but, it’s unlikely to be released soon, and besides I just got a new need for big virtual machines (hence the 32GB RAM). I got the i9 because its single-core geekbench scores noticeably higher than the i7, and I perform quite a few single-core tasks in a regular basis.

I love quiet machines, but I won’t be using this MBP for intense multi-core (except for limited occasions).

Thanks!