I have a Macbook pro 4,1 early 2008.

It's a great machine for surfing while the TV is on, but it's starting to act strange.

Sameple shot 1

enter image description here

These screenshots are both of a google sheet -- same one a few minutes apart.

I can see two possibilities:

A: My GPU is dying, and doesn't work in certain modes.

B: I've got a bad memory stick.

How do I diagnose which?

  • Are these pictures or screenshots? If they're pictures, next time you encounter the problem, try taking a screenshot. – NoahL Mar 1 '17 at 3:54
  • They are screenshots. Why? – Sherwood Botsford Mar 1 '17 at 15:12
  • Because a bad display would capture a clean picture whereas a bad GPU would capture the distorted picture. Your GPU is probably toast. – Allan Mar 1 '17 at 16:18

Run Apple Apple Hardware Test.

Apple Hardware Test (AHT) contains a suite of diagnostics that test the hardware of your Mac.

Here is the official support article by Apple: https://support.apple.com/en-us/HT201257

And the relevant instructions, "Turn on your Mac, then immediately press and hold the D key on your keyboard. Keep holding the D key until you see the Apple Hardware Test icon."

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  • The problem with the hardware test is that the problem vanishes -- for a while -- on reboot. – Sherwood Botsford Mar 2 '17 at 19:40
  • Can you elaborate? Because hardware test won't just test for hardware problems that happen at reboot, but test the hardware in general against some checks and give you a report. Did you try the hardware test though? Did test report anything? – Akshat Kedia Mar 3 '17 at 10:53

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