Recommendations:
1. Power down the server and reseat all removable components and ensure everything is securely seated.
2. Refer the user guide and use the system maintenance switch to clear the NVRAM.
Set the system maintenance switch 6 to on position.
Power on the server and wait for indication on screen that switch is in on position.
Power down the server and set the system maintenance switch 6 to off position.
3. Power on the server again and check status.
If step 2 was not successful or if you continue to receive errors/ beeps then refer the troubleshooting guide.
4. Do also check for bent pins, damaged cables etc on attached peripherals.
Documents for reference:
1. HP ProLiant DL380 Generation 5 Server User Guide
https://support.hpe.com/hpsc/doc/public/display?sp4ts.oid=1121413&docLocale=en_US&docId=emr_na-c00710263
2. HP Proliant Servers Troubleshooting Guide
https://support.hpe.com/hpsc/doc/public/display?sp4ts.oid=1121413&docLocale=en_US&docId=emr_na-c00300504