http://www.xcase.co.uk/X-Case-V12-Red-Black-p/case-xcase-v12br.htm
Look for the cost cutter 620, it states it has a single six pin connector so I'm assuming it provides more than 24 amps on the 12v rail/s so it should power the hd 4850 but I don't know how much power it has, I've contacted the...