Fan Issue

[Chaos Water]

I've got this strange issue with my case fans, when my computer boots onto the desktop for a split second all my fans slow right down then speed back up again.

Here's all my case fans I have at the moment if this helps

4 Arctic F12 120MM (2 intake/2 exhaust)
1 CiT LED 120MM (intake)
1 Coolermaster 120MM (exhaust)
1 Coolermaster 120MM LED (intake)

If it helps here are my system specifications

OS - Windows 7 Ultimate 64bit
CPU - AMD FX 8150 3.6GHz (AM3)
GPU - Sapphire Radeon HD 6850 1GB + XFX Radeon 6850 1GB (Crossfire)
RAM - 4 X 2GB Kingston HyperX Blu DDR3
PSU - Coolermaster GX650W
Case - Coolermaster CM690 II Lite
Monitor - Acer 23" HD 1080 3D LED Monitor
Keyboard + Mouse - Aula (Chinese make)

Is this normal or is there something not right?

 

[User4798]

if its just a split second then its fine even my pc did that. what motherboard do you have?

 

[knuckleonAMD]

Do you have any software that controls the fan rpms. Like Speedfan, or an overclocking utility if so it might be the program taking control of the fans. Probably nothing to worry about.

 

[Chaos Water]

No software controlling the fans, nothing has been modified in BIOS either, I have an ASUS Sabertooth 990FX motherboard.

 

[User4798]

I wouldn't worry about it. My old pc used to do it and it was fine also are the fans plugged into the mobo or Psu?

 

[Chaos Water]

All fans run directly to the motherboard and plugged in via the 3 pin connector.