During boot the LEDs cycle through system configuration processes, each with a specific POST code. Post Codes are documented in server board TPS/EPS. The SSR212MC2 uses the Intel® Server Board S5000PSL. The red, red, red, off code equates to E0h. You can view the POST Code Diagnostic LED Decoder in Appendix C of the S5000PSL Technical Product Specification. Always consider steps before and after the position of the LED’s.
The SSR212MC2 also uses the Intel® RAID Controller SRCSAS144E. Are you sure it's the server board beeping? Could it be the RAID controller? You can find information on the RAID controller at the SRCSAS144E Product Support page.