[SOLVED] Why does fan rev up every 30 seconds?

[Hwy14_]

New PC is in the shop. Old PC works OK just not nearly as fast. Every 30 seconds the fan revs-up for 3 seconds even when idling. Afraid something will wear out and I need this one for awhile. put in new 750 W psu and Evga geforce gtx 750ti. Task hang or stutter occasionally. It's like the PC revs up do to some big work then remembers there's not any. Does something need new instructions?

 

[JohnBonhamsGhost]

what fan; PSU, case, GPU, CPU cooler,..?
and what are you using to control the different fan's speeds?

 

[CountMike]

New PC is in the shop. Old PC works OK just not nearly as fast. Every 30 seconds the fan revs-up for 3 seconds even when idling. Afraid something will wear out and I need this one for awhile. put in new 750 W psu and Evga geforce gtx 750ti. Task hang or stutter occasionally. It's like the PC revs up do to some big work then remembers there's not any. Does something need new instructions?

Its reacting to temperature raise, temperature raises because of load so you might want to check what is running at those times.