Not sure if this is the same issue. But a while ago I had something similar to a new machine I had put together. It turned out to be simply that the 'kettle' mains power lead was not quite making full contact with the p.c power-source. This lead had been in use before, but I was using a new power-source with a fractionaly smaller socket. If your system had run for a while then shut down, that would indicate a temperature issue, but that doesn't seem to be the case. You still need thermal paste though
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