rMBP - fans kicking in when fast downloading?

[tadziak]

Hello,
I own a 15-inch 2012 Retina Macbook Pro. I noticed that when I download files at higher speeds (20 Mbit) the Macbook starts to get a bit loud. It happens also when I just test the speed of my line with speedtest.net. Is it normal behaviour for all the Macs?

 

[Jozone]

Fans ramping up will be in direct response in to increased processor usage, I'd run the speed test with Activity monitor open and see how much your browser processes spike (20Mbit downloads shouldn't really do this as that's a pretty negligible amount of disk write)

 

[2IS]

Fans ramping up will be in direct response in to increased processor usage, I'd run the speed test with Activity monitor open and see how much your browser processes spike (20Mbit downloads shouldn't really do this as that's a pretty negligible amount of disk write)

While true in it's strictest sense, it also depends on other factors. Is the wifi card riding on the USB or PCIe bus? Not really sure how it's configured on macbooks. If it's riding the USB bus there's more CPU overhead. There's also quite a bit more driver overhead for a network device then say, a drive to drive transfer. Then you also have slightly more overhead due to the fact you have another software layer in the form of a browser.

 

[Jozone]

While true in it's strictest sense, it also depends on other factors. Is the wifi card riding on the USB or PCIe bus? Not really sure how it's configured on macbooks. If it's riding the USB bus there's more CPU overhead. There's also quite a bit more driver overhead for a network device then say, a drive to drive transfer. Then you also have slightly more overhead due to the fact you have another software layer in the form of a browser.

I also don't explicitly know if it is on either USB or PCI bus, but based on my knowledge of older Macs, I would be shocked to learn that it would be on USB.

Based on my knowledge of having the same machine (rMBP 2012) -- and a 150mbit connection though, I can tell you that my machine doesn't ramp up fan based on download rates (YMMV however based on what protocols you're pulling that data down from though 😀).

 

[Toutou]

Fast data transfers of course produce some heat, but not very much. Your fans definitely shouldn't kick in just because of the download, but maybe if your Macbook was incredibly clogged with dust, this low amount of heat could make a difference.