GPU fan not working M17x r5

Hi, my alienware M17x R5 GPU fan has suddenly stopped working , I have opened and cleaned the fan, updated the bios and video card but still not booting up when temperature is high. I have ran a diagnostics on the fan itself and test are good ( fan spins when tested, fan passed test, but results say 0 rpm for min , max ?). I downloaded HMINFO64 to see if I can manually get the fan going , results are shown in screenshot. http://imgur.com/a/RKOxx , why isn't it showing fan 1 and 2 on separate functions, I cannot even access fan 2 as seen. I am not overly computer literate dell support are unable to help much , any help would be much appreciated , thanks