I have an Apple iMac “Core 2 Duo” 2.16 20-Inch (late 2006) model that is showing a common issue with an overheated GPU: errant horizontal lines and other artifacts. The problem is heavily reported on the Internet, and even noted at a Wikipedia page for this model. There is no real fix, but I might have found a cure for the overheating: “SMCFanControl” which is a utility that lets a user increase the minimum defaults for fan speed. Apple hasn’t released the specs on what is officially an unacceptable threshold for heat, but if my GPU is at 135° F, I’m thinking that’s too hot. The chart on the right is made by “Temperature Monitor” another handy tool for this matter.
A dab will do ya — when I cranked the fan, the temperature drop was remarkable. However, I don’t need to keep them cranked; by setting the sliders to 1/3 away from minimum, (see second graphic) that change has stopped the errant graphic drawing issues — for now.
Man, I can’t wait to try this. I’ve about had it with the crazy artifacts! Did your computer ever freeze up? Spinning Beach Ball of Death? I’ve read this is also related to the faulty GPU’s in some machines.
Kurt: I have experienced the SBBoD, (rarely system freezes) but in my situation I wouldn’t associate the two. Since I wrote that story some time ago, and since then my display problems have greatly reduced (though not eliminated.) I too would guess there’s a GPU issue. I have also installed the smcfancontrol on my laptop and I’ve been similarly impressed with the cooling performance.