You should be okay with a good copper cable. I would not recommend OCUK's 5m Value offering; you will need a high spec cable. Lindy do a cable with thick copper wires, the 36294, for £80 which failed me, but is worth a shot for you (if you can return it) before coughing up £180 + import duty for a FIBBR fibre cable. I ended up buying 10m cables because the extra cost over 5m was not significant and enabled me to put the PC in the corner. Note that the Lindy cable says that it's Displayport 1.4 compliant but when I got it, it had Displayport 1.2 on the packet. DP 1.4 may be for shorter cables only.