Processors (Intel® Core™, Intel® Xeon®, etc); processor utilities and programs (Intel® Processor Identification Utility, Intel® Extreme Tuning Utility, Intel® Easy Streaming Wizard, etc.)
This community is designed for sharing of public information. Please do not share Intel or third-party confidential information here.
12352 Discussions

Mobo shows red LED light for CPU issue, no display on monitor, no signal to keyboard, everything else is working normal.


For my PC specs, scroll all the way down.


I bought and built my own PC on January 11, 2020. Everything was working great. on April 13, 2020, I was browsing online, and suddenly my PC crashed, which was the first time ever on this machine. So I hold down the power button for a few seconds, PC turned off, I wait a couple of seconds, I then turned on the PC again, that was when I saw a red LED light on my motherboard indicating a CPU issue. All fans are working normally including CPU fan. I don't see anything on the monitor, yet the monitor works fine by itself. Also, the RGB on my keyboard does not light up when I turn on the PC, and it seems the keyboard can't communicate with the machine, yet the keyboard works fine by itself.


So now I have a machine that when I turn on, nothing shows on my monitor, and I can't even enter any commands through the keyboard to go to safe mode for example. It seems my only options are to either keep the machine running, or to force shut it down by holding the power button.


I tried many things to troubleshoot this issue, but nothing worked so far. I will list the things I tried below, (by the way everything was done outside the case to prevent the possibility of short circuit by the metal from the case):

  1. Check all cables and check PSU switch is on
  2. Turn off the PC, unplug all the cables, press the power button and hold for 20 seconds, plug everything back, then turn on the PC.
  3. Remove dust from all hardware
  4. Remove CPU, put CPU back again
  5. Turn on PC with only 1 RAM, then with no RAM, then with swapped RAMs
  6. Turn on PC without GPU, then again with GPU
  7. Remove old thermal paste, apply new fresh thermal paste.
  8. Remove GPU and RAMs, then turn on PC
  9. Remove GPU, remove RAM, turn on PC, then quickly switch off then on the PSU switch


Any help will be much appreciated!


My PC Specs:




GPU: ASUS ROG Strix GeForce RTX 2070 DirectX 12 ROG-STRIX-RTX2070-O8G-GAMING 8GB 256-Bit GDDR6 PCI Express 3.0 HDCP Ready Video Card

RAM: CORSAIR Vengeance LPX 32GB (2 x 16GB) 288-Pin DDR4 SDRAM DDR4 3200


PSU: CORSAIR CX-M Series CX550M 550W 80 PLUS BRONZE Haswell Ready ATX12V & EPS12V Semi-Modular





0 Kudos
4 Replies
Super User

You should really be asking these questions to ASUS.

You should also try a different power supply.

You have an i7-9700K. How old could the thermal paste be?


I am wondering if your power supply is undersized.

That the "red" led is on means nothing, which is why you should talk to ASUS.





Yeah I'm all over ASUS's forums and emails, but thought I might as well ask here since a red LED in this particular mobo means an error with the CPU according to the mobo's manual. The thermal paste was roughly 2 months old when I replaced it, It might be a PSU issue, I'm not sure. However, all the fans and RGBs are working normally and these are all obviously also powered by the PSU. It could be an issue with the CPU cable coming from the PSU, Though again, I'm not certain. Unfortunately, for me at least, I can't do much since all the PC stores in my area are closed due to quarantine..

Super User

That red led could be falsely indicating the processor.


Also , the power supply provides a number of different voltages. That the fans are running is not an indicator of a good power supply.


You are proceding under the asumption that the processor is bad. It may be. But, you should also test for other issues, like the power supply being bad or undersized. If you have onboard graphics, remove your graphics card.




If everything is connected properly and still nothing comes up on your computer’s screen, then the best way to identify it is an internal hardware problem or an external. You can try to press the NumLock or CapsLock Keyboard’s Key again and again, and check the keyboard’s NumLock or CapsLock light is blinking or not.