Try this
support.asus...
.com/Troubleshooting/detail.aspx?SLanguage=en&p=1&m=P8Z77-V%20LK&s=39&hashedid=J4TfLoZ8TXyFAkFb&os=&no=978
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Solution
1 the power LED is on
1.1 Make sure all cables are connected well
1.2 Please clear CMOS to have a try(refer to motherboard manual for details)
1.3 Keep the necessary components ( a CPU, a memory, a graphic card )on board to test
1.4 If there is still blank screen, please connect the connector of speaker to check if there is any beeps
1.4.1 If there is no beep, please contact your retailer for a check
1.4.2 If there is beep, please try to judge from the beep code as the following steps, if the problem still remains after the
troubleshooting, please contact your retailer for a check.
1.4.2.1 Memory issue: Beep (1 long 2 short)
A Clean the Golden Finger of memory
B Clean the memory slots
C Leave only one memory stick to test
D If convenient, please change different memory to test again
1.4.2.2 Graphics card issue: Beep (1 long 3 short)
A. Clean the Golden Finger of graphics card
B. Clean the graphics card slots
C. Try to test the onboard graphics card if there is onboard VGA integrated
D. If convenience, please change different graphic cards to test again
1.4.2.3 CPU issue: Beep (5 short)
A. Check whether the CPU is in our CPU support list
B. Check whether there are any damagers of your CPU or CPU socket.
C. .Check whether the CPU fan is correctly connected
D. Check whether the ATX_12V power cable is connected well
E. If possible try to test with another CPU
1.5 If the PC could POST after the troubleshooting as the steps 1.3, please plug components back one by one to find out which one may cause this
problem
2 the power LED is off
2.1 Make sure the power cable which connects to the front panel is well
2.2 Please swap a power supply for a try if possible.
2.3 If the problem still remains, please contact your retailer for a check.