PC will not come out of sleep mode

I few days ago I had the CPU FAN on my machine fail. I have ASUS P5KC mobo with intel LGA755 CPU. I got a new fan and heatsink and replaced those. Now is when it gets wierd. When I powered up the machine, it behaved the same way as when the fan was bad (green led on MOBO lit up, but nothing else). So, I checked all connections and then played with unplugging the lan cable - tried again and it worked. all good.
Now when the PC when goes into sleep mode, and I move the mouse or type keys on keyboard to wake it up, the fans spin up, but the machine does not wake up. When I then power the machine off, leave it for a while, mess with the lan cable (this lan cable issue may be a red herring, but I don't think so - it feels like unplugging and replugging it in allows a cap to dissipate or something (by the way - I eyeballed for bulging caps on MOBO but cound see nothing)), then the PC starts up. When it starts up, I sometimes see a "overclocking error" and sometimes a "CPU fan error". I'm prompted to select either "set bios to default" or "go into bios setup". I choose "default" and the machine displays "resuming windows" and all is good. The problem shows up again when the PC goes to sleep or if I restart the machine.
One other thing I should mention is that a while back the onboard LAN port acted funny (can't remember details), so I installed a LAN card and that resolved things then. Now the card is still installed and the onboard LAN and the LAN on the card behaves the same way.
Any ideas or help much appreciated,
Corky Seevinck
6 answers Last reply Best Answer
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  1. The problem might be the cmos battery. If it's empty, the bios looses the config and needs to reconfigure at every start. It sounds like the default setting doesn't include the wakeup from keyboard/mouse, but from PCI events, like the network card. Plugging the cable creates an irq from the network card and here we go.
    A new battery is cheap. Worth a try.
  2. Thanks for reply, I did what you suggested - replaced the CMOS battery. No change. Behavior remains the same. When the pc goes to sleep, It will not come back unless I unplug the pc for a while and then try again.
    Any other suggestions very much appreciated.
  3. Best answer
    So, that was the easy / cheap try. PSU would be next. Do have any chance to test an other PSU?
  4. I would need to buy a new power supply to test with it. Is there perhaps a way to test the power supply that I have?
    I'm struggling to understand two things going wrong at the same time. i.e. CPU fan and power supply. I guess its possible, but it seems to me that this is weird. Could it be that due to the CPU fan going out, something else went wrong?
    Thanks for your help
  5. Replaced power supply. Everything works fine. Thanks a lot for your help.
  6. Best answer selected by cseevinck.
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