Red CPU light on startup

Hey everyone,

I just built a gaming rig this past weekend and everything was working fine for a few days. Beginning yesterday, the red CPU light on the mobo is on when I start up. I shut the system down and disconnected the power supply and rebooted with everything working fine. Same exact thing happened this morning on start up. Any ideas? Should I be worried? It does eventually start up it's just really annoying and nerve racking every time.

My specs are:
Intel i5-3570k
Asus P8z77-v pro
Kingston Hyper X 8gb ram
Corsair M4 128gn SSD
Corsair Tx 650 PSI
HD Radeon 6580
Cooolermaster Haf 912
Coolermaster Hyper 212 Evo CPU fan/heatsink

12 answers Last reply
More about light startup
  1. Go thru your cpu options and check the voltages, and all its settings, could possibly be failing due to an incorrect setting. The good thing about this motherboard is it will keep trying to fix a problem during bios boot.
    The red light is a sign of an issue so go thru all the cpu options to determine what the problem could be, grab the manual to assist you as a guide.
  2. The other thing I would do would be to remove the CPU and heatsink and reinstall them. While you have the CPU out make sure there are no bent pins touching each other.
  3. So I just reset all the CPU configurations to the optimized defaults. Everything works fine but this happened yesterday as well, it seems the problems start with the first boot of the day then it boots fine thereafter. I guess I should report back tomorrow?

    I was told if there are bent pins or something similar it wouldn't boot at all, is that true?
  4. That is not true. I had one that would boot but have weird crashes. I straightened the pin and never had a problem since.
  5. Hi,

    From the manual in section 2.2.6 "on board LEDS" it says when one of these lights is lit it indicates a problem during POST. I would suggest at first to make sure all your physical connections are made and are secure. Make sure the power supply connectors are properly connected to both your 24 pin power connector and 8 pin power connector. Check and make sure you cpu is properly placed inside its socket, and that the heatsink is properly installed as well. After you hardware check try and update the BIOS. System stability is marked under that motherboards current BIOS updates.

    Good luck, hope I helped a little.
  6. Thanks a lot, I'll check all the cables right now but since it's booting fine and running fine right now, I'm going to wait until tomorrow morning and see if the problems persists before I remove the heatsink/CPU. I will post back on any further developments!
  7. I checked all the connections and everything seemed fine. Rebooted no problem.
  8. Have a look in the bios, check the cpu voltages and ram voltages , if any voltages are displayed in a red colour it means they are too high, lower them till they turn yellow or green and boot up and see if the problem still persists.
  9. Checked them, all seems fine. Might have found the problem, my bios was 0603 and I just updated it to 1015. According to the ASUS site, 0801 is need to support the new ivy bridge cpus. So hopefully that was my problem!
  10. Ah good to hear, the latest bios 1015 is good, looks like you worked out your problem as the 801 is for cpu compatibility
  11. Glad I could help mate ;) have fun with your new build.
  12. Thanks a lot :)
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