Graphic card's fan speed is -1 RPM

hadrianmt

Honorable
Sep 26, 2013
23
0
10,520
I took apart my Gigabyte HD 7870 OC last week to dust cleaning and reapply the thermal paste, and everything has been fine so far. However, I installed NZXT CAM on my computer yesterday to check the fan speed of my system, but it showed my GPU fan speed as -1 RPM despite all three fans still spinning just fine as well as the temperature of the card (idle at 27 celsius). Did I break anything that control the fan speed when I took the card apart ?