I do computer repair for an attorney who was recently contacted by a woman that left an iMac G5 at a local shop for repair in May due to overheating issues. She's returned it twice since then as the problem was not fixed, in fact the last time it would not turn on at all. During most of this time period, one particular Tech kept telling her to be patient, that it was almost fixed, that a motherboard had been ordered and was on the way, etc... That Tech no longer works there. I checked on Ebay just now and a working (p/n) 820-1783-a sold for $279.00. The whole item might be worth $600.00. After the first "repair", she paid $165.00 for thermal paste reapplication, memory upgrade to 2 Gbytes, and a reinstallation of the O/S.
My role in this is to provide technical information regarding the so that the woman and the attorney can make a decision on what to do (if anything). To that end, we picked up the G5 yesterday, and this evening I disassembled it and in addition to numerous examples of shoddy workmanship (broken screw stand-offs, missing screws, power wires clipped off and electrical taped together and several other examples) I found the strangest thing ever when I pulled a heat sink off off what looks like the GPU.
3 square pieces of copper sheet metal sandwiched between the GPU and the aluminum heat sink. Arctic Silver 5 on the GPU and Heat sink, but bare metal-to-metal contact between the middle piece of copper sheet metal and the two outside pieces. The Heat Sink fastens to the motherboard using plastic push-pins that have the "V" shape that expands on the back-side of the motherboard.
I can't decide is this is pure genius or pure stupidity. The thickness of the metal plates would increase the pressure against the GPU die, aiding heat transfer, but the metal is obviously hand-cut (not square), and has very sharp edges. Scratching a die can destroy it. And the absence of AS5 in the two middle layers has me wondering what the guy was thinking also.
Certainly this couldn't have come from the factory this way? And this model has "known issues" of overheating and there was a period where Apple was offering free repair to anyone that sent one in (now expired). Certainly this couldn't have been Apple's "solution", could it?
Because that might explain it, how someone was blindly following directions with the copper metal, but didn't understand that it was pointless unless the AS5 was applied throughout. At least that's my opinion.
So does anyone have an opinion or (even better) substantive information on this? I'm certain most of the "repairs" I am seeing are bad, but this might be the one shining example of competence. Or not, I can't say.
You can also see the CPU with the standard white plastic goop thermal compound in the upper right, with the CPU's heat sink inverted next to it.