Hi I have an RX580 Sapphire Pulse 8gb for my 4,1 flashed to 5,1 Mac Pro. I'm finding it impossible to find what I think is the correct power cable in stock in the UK. Does the cable have to be one specific type or can others be used? I found this which I think is the exact one: http://tinyurl.com/yb4thcw2 I also found this but I'm unclear as to whether it would work: http://tinyurl.com/yc2654lp Any cable advice and especially any links to the correct one if you've bought it recently would be appreciated. They all seem to be out of stock. Thanks!