My new, mid 2015 Macbook pro with duall GPU warms up with external monitor connected?

The temperature levels that you are reporting are well withing acceptable limits. As I respond to you, my 17" MBP is showing 57°c CPU temperature with nothing but a modem connected.

Ciao.

Hi Robert

Could you tell me which software you used to detect Radeon R9 M370X temperature? I have the same model, but cannot read GPU temperature using TG pro and istat. Thank you so much.

I use smcfancontrol to view the cpu temperature which is the temperature ive mentioned above. I use an tool called Hardware Monitor, which has been written by Marcel Bresink, to view the temperatures. The free version of this tool only reports the temperatures. But the GUI version says it doesnt support this macbook. In the app package is a commandline utillity which is called hwmonitor. If you run this from the shell it will generate the following output with all the temperatures you want. I made an automator workflow to view this output in a messagebox. Hope this is helpful.

SMART Disk APPLE SSD SM0512G (S2*********1): 30 C

SMC BATTERY: 28 C

SMC BATTERY CHARGER PROXIMITY: 42 C

SMC BATTERY POSITION 2: 28 C

SMC BATTERY POSITION 3: 27 C

SMC BATTERY POSITION Y: 28 C

SMC CPU A PROXIMITY: 47 C

SMC CPU X PROXIMITY: 56 C

SMC GPU 1 CHIP: 52 C

SMC GPU DIODE: 54 C

SMC LEFT PALM REST: 26 C

SMC MAIN HEAT SINK 2: 41 C

SMC MAIN HEAT SINK 3: 49 C

SMC PLATFORM CONTROLLER HUB: 42 C

SMC RIGHT PALM REST: 25 C

SMC WLAN CARD: 38 C

Smart Battery bq20z451 (1): 24 C

Dear Robert

Thank you so much for such prompt and detail reply. I've tried this tool in terminal and found that the two GPU readings(chip and diode) might be from INTEL IRIS PRO rather than from M370X, because I cross-checked with numbers from "TG pro" as attached image, that those 2 numbers are listed in the INTEL Iris Pro, not M370X. It's strange that a dedicated graphic card do not report temperature....

Thanx for your reply. Could be because the macbook model is still new, that it is not yet fully embedded in these software tools. My main question was regarding the cpu, and overall, temperature in my macbook. I noticed the increase of about 8 or 9 degrees in my cpu temperature as a result of simply attaching an external monitor. I was wondering if this is normal behavior for the amd/intel combination as my previous model (with an nvidia chip in it) hardly had any temperature increase when attaching a second monitor. That made me investigate further. The conclusion was that attaching the second monitor makes the AMD gpu wake up and the increase in temperature starts. Not only the GPU, but also other components like the cpu and even the power adapter. I was just wondering if this is normal behavior.