CPU Temp: temps idle will float upper 20C to 30's. Gaming/under load will be 40+
GPU Temp: idle starts also in upper 20s and will blow through 50s (this is still ok)
Motherboard Temp: should float in upper 20s-low 30s, always.
In the case you have not already done, set bios to defaults and only plug in the bare minimum to get your system up (get rid of your other accessories/drive devices).
your symptoms seem to point to heat. a computer that doesnt boot and does instant restarts is a hardware failure, most likely the CPU. If its not already fried, get an h50 or better to cool it.