It's a G0, so I agree with that. I may be on to something. I've been leaving my NorthBridge volts to auto, which can apparently cause my sort of issues. Someone elsewhere has been recommending I set it to 1.4v or so. If that solves it, heat may be an issue (with the NB anyway) but I have another 120mm fan I can install pulling air in from the front but I'll cross that bridge if I come to it. No.... when I come to it.
I've also found a huge thread about overclocking my chip, on my mobo so I'm hoping to pull some good info out of that if this NorthBridge business doesn't sort me out.
More news as events warrant.