If I hear a BEEP!!! on power up The monitor will come on normally and I can see normal post info. If no beep on Pwr UP screen comes on black and all else seems to be pwr'd up ok eg.hdd, fans,cdrom.
When an IBM PC-compatible computer is first powered up, it goes through a procedure known as
power-on self test (POST). If it passes, you hear a single beep. Errors produce what are known as
beep codes (patterns). Things that produce beep codes are missing or bad RAM, no graphics card, etc.
No beeps indicate it's not even getting
that far. Typical causes for this include poor CPU seating (make sure that the CPU socket is properly latched), a loose power connector, or a stuck or misconnected reset switch. Other physical problems include a marginal power supply or (rarely) a bad keyboard. Your keyboard is USB, so that's out.
Since it POSTs OK sometimes, it could be a BIOS setting like CPU clock speed, multiplier, or voltage, or possibly RAM speed, timing, or voltage.
When it
does boot, go to
setup. Check the
Hardware Monitor menu and look at the power supply voltages. Look at the
CPU Frequency & Voltage menu and make sure that it matches your actual CPU speed/multiplier/voltage specs. Look at the menu containing the RAM timings and (possibly) voltages to see if they are correct.
Note: Menu names may vary with the type of BIOS used.
Let us know what you find.
Unsolved 
