Its possible your heatsink is loose too, meaning that that temps are high as hell at "idle" windows but when someone thats processor intensive comes on, the temperature skyrockets and the system restarts due to a thermal warning. Just my 0.02$.
Everest would also be reading those values from the Mobo which wasn't changed...the only way to really tell if your volts changed due to PS would be a multimeter before and after changing, and you would need to monitor during load and idle
At any rate, those are probably single-rail PSU's, so you should be able to just stick MM probes into a molex/PCI-E plug to see what the 12V line is really doing, without going to the hassle of poking the motherboard itself, or wondering if the software knows what it's reading.
i7 2600K | ASUS Maximus IV GENE-Z | GTX Titan | Corsair DDR3-2133