Maybe check temps with a program like HWMonitor, to see if there's some real reason for the fans to go crazy. If temperatures are spiking, then you'd go the route of trying to improve that - checking for dust obstructing the coolers, checking that the CPU cooler is seated correctly, maybe reapplying thermal paste...
If not, then it's the path of trying to determine which fan is going crazy and why - maybe the fan itself is broken, maybe there's some wonky setting that needs to be changed, and so on.