"Odile Georgallides - Scheurer" said:
But when the PC is power up nothing happens, no boot, no beep, no video,
nothing.
I have to add that when I cleared the BIOS but changing the jumper to 2-3 I
had powered down but had not removed the power plug. There's a note in the
manual saying that if you do this it will prevent booting.
Did I fry my MB?????
HELP
The manual says:
"To erase the RTC RAM:
1. Turn OFF the computer and unplug the power cord.
2. Move the jumper cap from pins 1-2 (default) to pins 2-3. Keep the
cap on pins 2-3 for about 5~10 seconds, then move the cap back
to pins 1-2.
3. Plug the power cord and turn ON the computer.
4. Hold down the <Del> key during the boot process and enter BIOS
setup to re-enter data
Except when clearing the RTC RAM, never remove the cap on CLRTC
jumper default position. Removing the cap will cause system boot
failure!"
So, make sure the CLRTC jumper is back in the 1-2 position.
It should be harder to damage this circuit, because it has three pins,
and Asus should have been able to disconnect the dangerous power source
when the jumper is moved from the 1-2 position. If you look at the Intel
design guide, the power circuit for battery backup is shown here:
http://developer.intel.com/design/chipsets/designex/25252701.pdf (pg.167)
What this circuit shows is two diodes feeding power to the Southbridge
and the Southbridge contains the RTC and CMOS_RAM. Shorting this supply
causes excessive current to flow in the upper diode, sometimes burning
the diode. The current cannot be limited with a resistor, because the
operating current can be relatively large.
What isn't shown in the figure, is how to implement the "clear cmos"
feature. If the designer had used the "solder point" two pad method,
then it would be a sure thing that the circuit would be damaged. Since
Asus uses a three pin header on this board, they should be able to
avoid damage caused by +5VSB (which makes +3.3_sustaining) being
shorted to ground.
So, make sure the jumper is back in the 1-2 position. If the board
still won't start, then it must be damaged. You should also check that
your power supply is OK, before you decide to return the motherboard.
See if the green STANDBY LED is still glowing on the board, because
that would mean that the +5VSB from the power supply is still working.
If you still have the green STANDBY LED lit, CLRTC in 1-2 position,
and the board still won't start, then return the motherboard.
Paul