Update your post to include full system hardware specs and OS information.
Include PSU: make, model, wattage, age, condition (original to build, new, refurbished, used)?
Disk drive(s): make, model, capacity, how full?
Other connected peripherals?
How many pc case fans? Fans: make, model, specs?
What specific connections are being made from PSU, motherboard, etc. to the fans? All fans.
Are you using only the cables that came with the PSU?
All too easy to make such connections that, although they can physically be made, should not be made.
More information and details needed.