The low values for 3.3v and 1.5 v are odd. But when a computer freezes up after running for a while and then will not re-start until an hour later, I have to suspect overheating. It runs OK while the temps rise, then gets so hot the auto protection system kicks it out. After that it has to cool down (with no fans running to help!) before it is allowed to re-start.
I would check out the various termperatures, particularly the CPU temp, as it runs. You may need to remove and re-install the HSF unit(s) and the thermal paste to get cooling working properly.