hello hello, this is for anyone who think they can help.
installed a new a7v400-mx mobo into an older case. The computer is not even
starting up at all. The mobo has a 2 pin atx power switch lead and my power
supply does not. is this the problem or is there something else that will
cut off the power? thanks in advance.
The power switch is set up as follows:
____________________
|
Computer_case_power_switch------->PANEL_header--
| |
| |PS_ON#
| |
| 20 pin ATX
| power
| connector
--------------- | ------
|
PSU Power
Supply Unit
The computer case has a power switch on it. The power switch has
two wires and a two hole connector on the end. This is connected
to the PANEL header, which is usually located in the lower right
hand corner of the motherboard. The "ON" signal is called PS_ON#
and after going through a couple of chips on the board, shows up at
the 20 pin ATX power connector. So, there is one signal that turns
on the PSU, and that signal is buried amongst the other 19 power
signals on the fat power supply cable.
To turn on the PSU, the motherboard grounds the PS_ON# signal.
A momentary contact on the computer case switch, makes a steady
ground signal on the PS_ON# wire. If later, you press and hold
the computer case switch for 4 seconds or more, the PSU will shut
down again.
Now, on to things you can check:
1) Plug in the PSU and flip the switch on the back of the PSU to
"ON". The PSU sends +5VSB down the power supply cable. This is
the power that the chips need to be able to read the computer
case power switch which is connected to the PANEL header. If
your PSU is healthy, you'll see the green LED on the motherboard
glowing. That glow means +5VSB is on the motherboard. Never
insert or remove hardware from the motherboard while the green
LED is glowing. I like to unplug the PSU before doing any work
inside the computer, and when I do that, the green LED should
stop glowing. (This is a conservative safety precaution to
prevent expensive accidents.)
2) Check that the CPU heatsink is properly installed, that there
is either a thermal pad or some heatsink paste installed between
the CPU and the CPU heatsink.
3) Make sure the CPU fan is plugged in.
4) And, the most important thing on this motherboard, check the
DSW dip switches. The manual doesn't make it clear what setting
to use. A nice safe setting is to put the five switches in the
"OFF" position, and that will set the CPU clock to 100MHz.
That will allow you to get the computer to boot. If that works,
you can shut down the computer (press and hold power switch for
four seconds) and flip the switches to whatever speed your
processor needs. For example, if the FSB rating of the processor
is 333, then choose 166 for the switches, which is OFF-ON-ON-ON-ON
from left to right (position 1 through 5).
HTH,
Paul
)