In some cases, a CMOS Clear must be performed to reset the BIOS to factory defaults. In troubleshooting cases, a CMOS Clear is recommended so that the system reinitializes itself independently of BIOS settings.
The process of CMOS clear differs with many manufacturers, often there is a CMOS clear jumper that needs to be set. In desktop or workstation motherboards there can even be a dedicated "CMOS Clear" button. So it is always worth having a look into the manual. Various processes are described below.
CMOS Clear Supermicro
First, turn off the affected system and remove it from power. Once the server is open, you should locate and remove the CR2032 button cell battery. Below is an example image of a Supermicro motherboard.
Supermicro Mainboard H12SSL-NT ©Supermicro
https://www.supermicro.com/manuals/motherboard/EPYC7000/MNL-2314.pdf
Next, the CMOS clear jumper must be shorted, a flathead screwdriver is needed for this.
All Supermicro mainboards have a jumper "JBT1", the position is different on every mainboard and should be checked in the manual before. At the jumper JBT1, the screwdriver must make contact between the 2 soldering points.
Apply a little pressure for 5 seconds, then remove the screwdriver. Afterward, the battery can be plugged in again and the system should boot up after you reconnected the power cord.
CMOS Clear Gigabyte
Gigabyte uses a jumper for the CMOS Clear, there the procedure is a bit different. Gigabyte uses CMOS Clear jumpers, which have to be moved. By default, they are on pin "1-2" for the CMOS Clear they have to be moved to "2-3". Following is an example picture of a Gigabyte motherboard.
Gigabyte Mainboard MZ92-FS0 ©GIGA-BYTE
https://download.gigabyte.com/FileList/Manual/server_manual_r282-z93_e_10.pdf
The system must be switched off and removed from power, then opened up. The CMOS Clear jumper is labeled on the mainboard and defaults to pins "1-2" for the CMOS Clear they have to be moved to "2-3". Now you have to wait about 15 seconds and finally set the jumper back to pin 1-2. Then the system can be connected to the power and switched on again.