My computer has been running fine for 4 years, but yesterday it starts to exhibit odd behavior:
After I shut down the computer, the CPU and GPU fans start spinning at full speed (everything else seems to be turned off). The only way to stop the fans is to cut power by switch on PSU.
Now, if I turn on power by PSU switch, there are two scenarios:
If I left computer without power for longer time (like for a few hours), all fans (even PSU and case fans) now start spinning at their lowest speed, case LED is on, I can operate DVD drive, ... but motherboard itself seems to be turned off (onboard display is off) and I cannot turn on the computer by case button.
If I switch PSU power off / on quickly, only the CPU and GPU fans start spinning at full speed, and I can turn on the computer normally by case button. After the computer is turned on, fans immediately slow down and everything is OK.
I checked the cables with no results. I also inspected components visually (for things like failed capacitors) - everything seems fine.
I have no idea what component might have failed. Could you please help me?
- Windows 7
- no overclocking
- CPU: Intel Core i7-860
- MB: Intel DP55KG
- GPU: Sapphire AMD HD 5850
- PSU: Enermax Modu87+ 500W
- Case: Fractal Design Define R2
- case fans are connected to motherboard (not PSU)