I am buying the parts for my new PC: Zotac 9300 with a dual core 3.16 ghz processor, 4 GB ram and a 1 TB HDD. I figured i would need a pretty powerful supply so i was looking for the 320 watt opus. On the opus site they only list 360 watt but when you click to buy it only gives you a 250 watt. So where would i look to buy them as the MP3car store is sold out it looks like. And why the differences in wattage from here to the manufacturer site