Many reasons that will give you a yellow light. What has caused this issue, it was working fine and all of a sudden it stopped - was there a power glitch?, have you moved the computer as sometimes the memory and or other connections inside get loose. I would open the box if you are comfortable - ALWAYS UNPLUG THE POWER. clean the inside of the machine and check to see if nothing has been moved and the memory is installed properly. Hopefully that should resolve the problem else you may have a bad motherboard and or a power supply that needs replacement. Take it to a repair shop if you you are unable to work on it.

I had thi issue too, but with a little complications. It was fixed in the following pathology. Close background apps and processes. Close open tabs in your browser. Run a malware scan. Increase airflow around your computer's vents. Clean out dust in ports and vents. Turn off your computer, wait a few minutes, and then turn it back on again.