HP dc7900 - Convertible Minitower PC Troubleshooting Manual page 21

Table 2-2 Solving Power Problems (continued)
Power LED flashes Red four times, once every second, followed by a two second pause, and the computer beeps four
times. (Beeps stop after fifth iteration but LEDs continue flashing.)
Cause
ENWW
Solution
the power supply adapter with the HP-supplied USDT power
supply adapter.
Solving Power Problems 15