• Code: 820
• Description: Self-Diagnostic Error: CPU
  An unexpected exception or interruption has occurred.
• Causes: • Defective controller board • Software defective

• Code: 821
• Description: Self-Diagnostic Error: ASIC
  The ASIC returned an error during the self-diagnostic test, because the ASIC and CPU timer interrupts are compared and determined to be out of range.
• Causes: • Defective controller board

• Code: 822
• Description: Self-Diagnostic Error: HDD
  The hard disk drive returned an error during the self-diagnostic test.
• Causes: • HDD defective • HDD connector defective • Defective controller board

• Code: 823
• Description: Self-diagnostic Error: NIB
  The network interface board returned an error during the self-diagnostic test.
• Causes: • Network interface board defective • Defective controller board

• Code: 824
• Description: Self-diagnostic Error: NVRAM
  The resident non-volatile RAM returned an error during the self-diagnostic test.
• Causes: • NVRAM damaged or abnormal • Backup battery has discharged • NVRAM socket damaged

• Code: 826
• Description: Self-diagnostic Error: RTC/Optional NVRAM
  The RTC (real time clock) or optional NVRAM returned an error during the self-diagnostic test.
• Causes: • RTC defective • NVRAM defective

• Code: 827
• Description: Self-diagnostic Error: RAM
  The resident RAM returned a verify error during the self-diagnostic test.
• Causes: • Memory malfunction

• Code: 828
• Description: Self-diagnostic Error: ROM
  The resident read-only memory returned an error during the self-diagnostic test.
• Causes: • Defective controller board • Firmware defective