http://www.tech-forums.net/pc/f76/up...-guide-137927/
HEC is listed on the Brands to Avoid list.
To answer your questions:
1. Your PSU may not supply sufficient power to all yoru components, and your PC could randomly shut off.
2. Yes, you need a PCI-E plug from your PSU to power the card.
3. Use RivaTuner to boost of up the fan speed; I have mine at 70% normally, and around 90% when I'm doing heavy gaming.