I'm getting a System Fan error 90B on HP Envy Beats edition 1114. on HP Support website i have found solutions like hardware reset and ... and i have tried them all but the same error still exist. so according to them i have to replace the fan. problems is there are 2 fans! which one should i replace? because from the looks of them, both are spinning and i can feel almost the same amount of air pressure produced by both fans (on my hand). i can replace them both but the owner doesn't want to pay too much. can anyone help?