Re: A7V400-MX Question
- From: nospam@xxxxxxxxxx (Paul)
- Date: Tue, 16 May 2006 06:35:49 GMT
In article <1147744107.452199.31600@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, "Marco
G" <marc.garrison@xxxxxxxxx> wrote:
The mainboard mentioned in the topic will not POST, and gives no beep
codes. Removed all components one by one, and tried known good memory
and vid card. Basically I'm trying to get it to at least throw a beep
out so I know the motherboard is good, but i'm begining to suspect that
it isn't. Just looking for a second opinion before I spend the dough
on a new motherboard. Thanks.
Was this motherboard in a working system, which has stopped working ?
Or is this motherboard a new one, right out of the box ?
First, observe whether the green LED is lit on the motherboard.
The power supply has to be switched on at the back, in order for
the power supply to give the necessary +5VSB (standby voltage)
to the motherboard. That makes the green LED light up. The power
switch on the front of the computer case, cannot start a motherboard,
unless the green LED is glowing. So first verify that you
have that much power running to the board.
If the LED is glowing, the next step is to try the power switch.
You can disconnect the power switch, and plug the reset switch
into the power switch pins on the PANEL header. In that way, you
can test to see if you have a bad power switch, by trying the reset
switch instead. You can also use a slot-shaped screwdriver, to
momentarily short together the two power switch pins on the
PANEL header. The screwdriver makes a good substitute for a power
switch.
If pressing the power switch on the front, causes the PSU fan to
spin, the computer case fans to spin, and so on, then you know the
main power rails have started successfully. You cannot expect beeps
unless you get that far.
The minimum config is motherboard, CPU/heatsink/fan, and PSU.
That should be enough to beep and complain about missing RAM
or missing video card. To beep, the processor has to execute some
BIOS code, and as you observe, hearing some kind of beep at least
proves the thing is not completely dead.
If the fans spin, and there is no beep, the PSU is not completely
off the hook. If you own a multimeter, you can probe where the wires
enter the nylon shell of the 20 pin connector, and probe the voltages
present on the connector. You can check the +3.3V, +5V, +12V, and
the -5V and -12V. The power supply market is a tricky one, and I've
heard that at least one product was missing a -12V wire. While
motherboards don't have too much excuse to be using -5V, sometimes
the COM port RS-232 needs the -12V. In any case, have a good look
at your supply, as you never know whether the Asus motherboard
needs one or both of those two rails. (If you have an older
pre 2.0 version of ATX supply, try that instead of your current
supply, even if it is only rated at 250W.)
HTH,
Paul
.
- References:
- A7V400-MX Question
- From: Marco G
- A7V400-MX Question
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