Macbook 3,1 GPU Overheat? Crawls /w Artifacts

I have a Macbook 3,1 with Mavericks on it. It's the 2.4/2.2GHz model with a NVIDIA GeForce 8600M GT 128 MB graphics card in it. I'm currently using Mac Fan Control to adjust the Fan speed depending on the heat of the GPU diode. When the diode gets above 60c, the computer will either, put up artifacts on the screen, e.g., hovering box around the mouse, or big green shades (they look like a cracked glass screen) over the entire screen, OR the computer will completely lock up. On occasion, when the artifacts appear, (I was using SMC Fan control at the time) I would crank the fan up to maximum, and could regain control of the computer.

I've completely blown out the fans, and under the motherboard as best as I could, but have ordered some new thermal paste for the heat sync and CPU/GPU equipment. But.... does anyone have another suggestion? Does this fit the qualification for a motherboard reflow? And, does anyone reflow the motherboards here in Oregon, or should I try the "bake it in the over at 250" approach?

I believe I have a hardware problem, but would love to have you lie to me about that, ha. Really though, if you have any suggestions that'd be great.

Thanks!

Just though I'd reply that I followed a guide online about baking the macbook. I disassembled it, put it in the oven at 375 degrees for ~8 minutes, and then reassembled it. I've yet to experience artifacts, but the fans are turning much faster now. Before they'd hardly spin (Roughly 2000RPM) and I had to use a fan control to compensate.

I'll post back more later if I experience any changes.