I recently purchased a Thunderbolt Display to use with my Late 2011 MacBook Pro 13-inch. I was quite happy with the overall performance until I noticed that the only fan in the laptop started running at overly high speeds (over 6000 rpm) to cool off temperatures surpassing 90C (194F) on the temperature diode/CPU die. This happens every time I watch a video and gets worse if I do so on full-screen mode. Most other tasks produce around 70C (158F) and 4000 rpm.

This of course not only produces annoying noise but reduces the lifespan of any affected internal components. This positively does not happen when the TD is unplugged. I have a couple of questions I was hoping people out there could help me with:

(1) Will any similar (27 inch, 2560x1440) monitor produce the same behavior or is this a thunderbolt interface issue? Can my MBP drive a monitor with these specs without overheating?

(2) How damaging can high temperatures be? Am I slowly killing my computer with the TD?

(3) Am I asking my hawrdware for too much or is Apple basically marketing a 'computer overheater'?

Thank you!

  • 2
    What is CPU usage during these times? There might be some runaway process in the background, taxing the CPU. Try opening Activity Monitor (in /Applications/Utilities), right clicking its dock icon, then click Show CPU History in the Dock Icon menu. Leave it running and keep an eye on CPU usage when things get toasty. Tell me what processes you notice use the most
    – Alexander
    Commented Feb 22, 2014 at 1:53
  • 1
    It's mostly Chrome/Chromium helpers, the ones handling video. Interestingly, Flash gets it 10C hotter than HTML5. Your opinion on question (1)?
    – Zweifler
    Commented Feb 25, 2014 at 17:57
  • Extra monitors don't really tax the system. Sure you need a bit more video memory for frame buffering, but just having an extra monitor plugged in won't really decrease performance or increase heat. One of the best ways to combating the heat flash player can cause is the Click to Flash plug in for Safari (it's actually my main reason for using Safari). It prevents flash applets from running automatically, and can replace the youtube flash video player with a built in (MUCH more efficient) quicktime player.
    – Alexander
    Commented Feb 26, 2014 at 10:34
  • 1
    @XAleXOwnZX I disagree with you statement regarding that extra monitor does't tax the system. It indeed taxes it. For example I have first hand experience with old MB with x3100 iGPU and it is clearly visible that just connecting external display will get machine hotter. On the other hand owner should be happy he doesn't have standalone GPU since those Radeons in 15 and 17" MBP proven to be troublesome
    – iskra
    Commented Dec 28, 2014 at 15:19

2 Answers 2


i don't know why, but when i stopped using the mag safe from the thunderbolt display to power my MBP, and just used my normal power adapter, I quit having the overheating problem. I've taken my display to apple several times and they can't figure out why it keeps overheating and turning off.

  • Fascinating. Attempting this right now and it seems to work.
    – Translunar
    Commented May 15, 2015 at 14:23

The Sandy Bridge i5 CPU in your Mac is designed and packaged to run at 100°C so I wouldn't be concerned with the temperatures you are monitoring. The blowers should be running when you approach that internal temperature.

If you log out and let the Mac idle for 5 minutes and en log in, the blowers should be back at 2000 RPM and the temperatures substantially lower.

  • Yeah, Tjmax is 100C but there's too much noise and so much heat can't be good in the long run. Your opinion on question (1)?
    – Zweifler
    Commented Feb 25, 2014 at 17:54
  • I think you'll run hot with even an Apple Cinema Display running 1900x1200 resolution. My experience in repairing Macs, using Macs is that you might call AppleCare or swing by a genius bar to get a baseline temp recording on the record for that serial number but not see any practical decrease in lifespan even if it runs hot all the time. Your battery will likely last less than it could if it never got warm, but again, that fractional cost is low to repair vs not have a productive computer pushing pixels.
    – bmike
    Commented Feb 25, 2014 at 18:00
  • Also see clamshell mode heat and nvram settings to keep the screen off more often in case these help.
    – bmike
    Commented Feb 25, 2014 at 18:01
  • Thanks (XAleXOwnZX & bmike) for the advice and insight. I am going to try a new monitor soon and will report back (if I remember to do so :) ). Let's see if I can drive a 2560 monitor without the heat and noise...
    – Zweifler
    Commented Feb 28, 2014 at 16:44

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