Hey there - is a 1000W Gold-standard PSU enough for 3 of these cards, AMD Sempron CPU and 3x powered PCIe risers? The PSU I was looking at is the Corsair RM1000:

http://www.corsair.com/en/power-supply-units/rm-series-power-supply-units/rm-series-rm1000-80-plus-gold-certified-power-supply.html

I was also looking at the Corsair AX1200 PSU (1200W) but it costs 100 euro more than the RM1000, and if I don't need 1200W, might as well go for the RM1000. Thanks!