Dell Technology Guide
Page 275
... the keyboard. C M O S C H E C K S U M E R R O R - C P U F A N F A I L U R E - If the computer malfunctions, you received is not listed in the table, see "Contacting Dell" on the Dell Support website support.dell.com. ALERT! Possible motherboard failure or RTC battery low. Replace the CPU fan (see the Service Manual for your computer or see "Contacting Dell" on page 337 for assistance). Diagnostic Lights for the topic...
... the keyboard. C M O S C H E C K S U M E R R O R - C P U F A N F A I L U R E - If the computer malfunctions, you received is not listed in the table, see "Contacting Dell" on the Dell Support website support.dell.com. ALERT! Possible motherboard failure or RTC battery low. Replace the CPU fan (see the Service Manual for your computer or see "Contacting Dell" on page 337 for assistance). Diagnostic Lights for the topic...