Question CPU LED on boot SOMETIMES.

Jun 6, 2019
Apu- Ryzen 5 2400 g
Motherboard - MSI B450 Tomahawk
2 x 8 gb sticks of ram ( Corsair Veng)
Samsung Evo 860 m.2 ssd 500 gb
Stock cooler
Integrated graphics
WD 1 tb hdd
Windows 10
Corsair Gold rated 650 psu

First build ! Had issues (red cpu led) after completion of the build , but after clearing the CMOS, I was able to install the OS, and get to gaming. EVERYTHING runs extremely smooth, and I couldn't have asked for faster boot times ( for what I need). However, while in the BIOS monitoring cpu temps and such, I accidentally clicked the boost function, realized what i did, then turned it off, as I really did not know what it did. Upon exiting the BIOS, they notified me of changes that I made, but since I felt i disabled the boost , I chose to save and exit, AND that is when the issues began. Immediately after leaving BIOS, red CPU light came on , forcing me to power off the machine. Upon reboot, everything would be fine, but after every trip to the bios, and on a few restarts, the red cpu light would come on and I could not boot. I went into the BIOS and restored default settings. This seemed to fix the issue as I was now able to roam freely back and forth between BIOS and OS. Last night My PC fell asleep, and upon trying to wake it up this morning, THE RED CPU light came on! I tried rebooting several times, but only after unplugging PSU was I able to boot properly.

Have a feeling there is some underlying issue but am extremely inexperienced and would love any help possible ! Writing from my pC now! Lets hope it keeps booting! Please excuse any misused terms as Im Greeeeeen .


Apr 3, 2018
It can be a temperature problem. Does the cpu fan work properly? Is the cooler properly positioned? Is there thermal paste between the cooler and the CPU?

Download a temperature control program such as HWinfo or HWinfo64 to control temperatures from windows instead of from the bios.

If you make any changes, under no circumstances turn on the PC without the cooler placed and the fan connected.