First and foremost.. Even though the Motherboard came free with the Videocard, your first mistake was using it. eVGA does make the best videocards, but they aren't well known for their motherboards.
You're problem could just simply be, "an unstable motherboard".
If it's not stable it won't provide the proper voltages to the CPU, RAM, Videocard, ETC... hence (Hard Crashes).
As far as a bad PSU goes, it could be... But given the fact that you are using a free eVGA motherboard, i'd tend to point my finger at it.
You could have a PC Power and Cooling PSU, with the strongest rails on the planet, but if the motherboard isn't stable, it's going to give you plenty of head aches.