Member Avatar for cuivenion

Hi, I'm running a mid/late 2007 Macbook Pro with Mavericks:

Click Here

When I connect a second display the cpu temp goes through the roof, 90C with the fans at max. When I disconnect the screen the temperature comes down. Temperature Monitor shows that it's the CPU's not the GPU that are getting hot. I've looked in Activity Monitor and there's nothing taking up a large amount of CPU that would seem to be causing this.
I've cleaned out the Mac in the last 5 months so I doubt it's a dust build up problem. Any help would be greatly appreciated.

  • 2 Contributors
  • 2 Replies
  • 355 Views
  • 22 Hours Discussion Span
  • Latest Post Latest Post by cuivenion

Dani AI

Generated

Quick, practical checklist to isolate why an external display makes the machine run hot (software vs. hardware), plus a few safe diagnostics to try before opening the case or paying for repairs. ’s BIOS suggestion isn’t applicable on Macs — there isn’t a user-accessible BIOS option to toggle GPUs — but you can observe or force GPU switching with a utility like gfxCardStatus when applicable. (gfx.io)

  1. Rule out the adapter/cable: test with a different monitor and a different connection (avoid USB‑to‑video/DisplayLink adapters if possible — those drivers often put extra load on the CPU). If the problem only appears with a particular adapter or dock, that’s the likeliest culprit. (plugable.zendesk.com)

  2. Narrow software vs. driver problems: boot to Safe Mode (disables third‑party kernel extensions and login items) and test with the external display attached; if the issue disappears it’s probably a driver or extension. Also try a second user account to rule out per‑user login items. (support.apple.com)

  3. Reset low‑level controllers and test hardware: reset the SMC (controls fans and thermal management) and NVRAM/PRAM, then run Apple Diagnostics (Apple Hardware Test on older models) with the display attached to see if it reports errors. If SMC/NVRAM resets don’t help and diagnostics return GPU/sensor/fan codes, it’s likely hardware. (support.apple.com)

  4. Quick command‑line checks for odd drivers or runaway processes (run in Terminal). If Safe Mode helped, look for non‑Apple kernel extensions or background daemons that load when normal booting:

    
# show non-Apple kexts
kextstat | grep -v com.apple

live CPU view (sort by CPU)

top -o cpu



If kernel_task spikes or fans stay at max despite low visible CPU use, that process is often responding to a thermal/sensor condition (it throttles CPU to protect the hardware) — that points toward a failing sensor, fan or board issue and you should collect diagnostics and seek service. ([support.apple.com](https://support.apple.com/en-us/102172?utm_source=openai))

If these steps don’t show a software cause, capture the Apple Diagnostics codes and take the machine to an Apple‑authorized technician (or post the diagnostic reference codes here).

Recommended Answers

All 2 Replies

Member Avatar for rubberman

Have you connected with your Apple "Gurus" about this issue? It certainly isn't normal behavior, though I don't know a lot of people who use dual displays with their macbook laptops. I use dual displays on my Windows 7 laptop (Lenovo) and it doesn't seem to affect the cpu temperature - it is running an nVidia graphics chip set for both. I think your system has both an Intel GPU as well as an nVidia GPU, so if that it the case, you might try to disable the Intel GPU in the BIOS since that is likely co-located with the CPU, hence the heat increase you are experiencing.

Member Avatar for cuivenion

Hi, it doesn't have intergrated graphics, it has a separate nvidia gpu. According to Temperature Monitor it's the 2 CPU cores that are getting hot. I use the Macbook Pro to run karaoke nights using Virtual DJ hence the second screen. It's not the software either as this happens when Virtual DJ is shut down.

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.