No way he is getting 50% less power usage with OC and under-voltage. My system without the this card is using 1324W and with it 1513W.
Yes you can use x1 or x4 or x8. No performance penalty. All you need is a riser cable or you need to take back of a pci slot away.
Its possible 25% UV and 25% UC is 56%
Core is over-clocked from 725 to 775. So no... And I just tested settings that he posted. Best case 100W but I think is more 130W. Need more time to get average since I have 8 cards in. If this would work it would be grate and I wouldn't change it back but it doesn't. Even when you have mem at 75 not 300 as he told us. So I resetting to what I had.