Power surging fans and harddrive

By briancb2004
Nov 4, 2007
  1. I have an HP desktop that started surging. The fans start to turn on then shut down then turn back on. Usually after about 2 minutes they start running normal. I thought it might be the power supply so bought a new power supply but is still doing the surging. Was able to get the computer to boot once on the old power supply but haven't been able to since. Has anyone heard of this before?
  2. Nodsu

    Nodsu TS Rookie Posts: 5,837   +6

    Smart fans are supposed to do that. The fan adjusts its speed according to the system temperature. At startup the system is very cool and the fan would have to spin below its minimum speed. So, instead it spins at its minum speed intermittently.

    Or do you mean that your fans go at full speed, then stop, then go again?

    And what about the hard drive?
  3. briancb2004

    briancb2004 TS Rookie Topic Starter

    They go full speed and then slow down to almost nothing then go full speed. The hard drive does the same thing you can hear it starting up then it slows down. Also you never get that first beep when you start you computer.
  4. Nodsu

    Nodsu TS Rookie Posts: 5,837   +6

    A hard drive cannot slow down. It can either accelerate to full speed or spin down to full stop.

    It sure looks like a power issue. Since you have replaced the power supply.. Try disconnecting all system components and try with a barebones system - motherboard, CPU, RAM, video. Ideally you would even remove the motherboard from the case to rule out any shorts.
  5. technicalfury42

    technicalfury42 Banned Posts: 62

    It sounds to me like Q-Fan/Smart Fan, which is probably enabled in the BIOS, if it is doing this in windows.

    This usually happens when the processor or case temperature is very near the ramp-up threshold. The fans spin up, reducing the temperature beneath the threshold, and then it slowly climbs back up, causing them to spin up and repeat.

    Either try to improve ventilation, reseat your HSF w/ Artic silver, or download fan management software and change your thresholds.

    And once a harddrive has "spun up" to its RPM (i.e. 7200RPM), it does not vary in speed during normal operation.

    If you mean the computer won't boot up at all, and the fans go fast like normal, then slow down, and repeat and equal intervals, then you have a different problem. Do you have both power connectors plugged into the motherboard?
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