One GPU fan never turns on

[Saajuk]

I run two 980s in SLI. Both fans work and are running at boot up but while under load and gaming only the top GPU has fans running. The bottom one just twitches a little bit every couple of seconds. Temps seem to differ around 20 degrees the hottest one being the top (64-70) and bottom is around (43-45). I tried switching the GPUs. Both ran at boot up but still only the top ones fans ran during gaming and bottom on twitched. How can I get both fans to run? I have had the pc for about 3 years not even sure if this was a thing from the start, never really paid the much attention to the fans till now.thanks.

 

[24601]

Many cards nowadays turn their fans off if the temperature is low.

It's normal.

 

[pandemonium]

Your primary card will always run hotter than the secondary. The reduced room for air flow and increased demand by driving display(s) increases the temperature.

As for the fan not spinning I wouldn't worry about it as long as it does spin when temperatures increase.

If you want to control when fans turn on at what temperature and at what RPM, look into getting software for that. MSI Afterburner works for any card (regardless of aftermarket brand) and is pretty universally used. Otherwise, there's a plethora of software out there to use if you have a particular preference.