Ive just finished building my HTPC and it's run ok for about a week. It has now started to power down unexpectedly. First it would shut down when ripping CDs but has now started powering down during boot up. I have a Zalam 300 W power supply with an AMD 2000 and the usual Revo, Radian and Nebula cards etc. Is the power supply too small? Has anyone any fault finding tips?