CPU_Fan Port performing slow

[BluDYT]

on my Asus crosshair VII Hero MB i have noticed that the CPU fan port runs slow it was only running my fans at 300rpm when i set it to 100% i was able to get 600-700 rpm regardless of the fan being used. if i put it into a sys fan port itd be at 1200 idle upward to 2000rpm but the board needs a fan installed in that port to boot however. is this maybe a setting in the bios i can override this or is it just broken? my 360 rad is able to keep temps mostly in check under load with the 2 other fans working properly however with overclocks its almost always into the high 80's low 90's C