Help! No POST, no video...

[TM]

fans run. And the computer won't power down unless I unplug it. When I
re-plug, computer turns on instantly WITHOUT power switch, but same symptoms
persist: no POST, no video, fans run, can't turn off with switch, etc.

This is a late-2006 build that has been flawless up to this point. No
warning given.

Asus M2NPV-VM
AMD 64 Athlon X2 3800+
Corsair XMS2 6400 DDR2 512MBx4 (dual mode 800 MHz)
Maxtor Barracuda 250 GB SATA
ATI TV Tuner Card
CD R/W
DVD
Floppy
Linksys Wireless G USB Adapter
USB wireless KB and mouse
Antec Minuet 300 Case with 300W PS
Samsung 23" LCD monitor

Symptoms persist with or without memory, CPU, drives, USB devices or tuner
card connected.

3.3V and 12V power supply rails test OK with multimeter. The (supposedly) 5V
"Power_Good" rail (gray wire on 24-pin connector) tests at 95mV, but I'm not
sure if this is significant with the Antec 300W power supply.

Swapped CPU. Still no go.

I've done all of the testing I can think of. I can't swap parts with my
other rig, since it's IDE only and has only 20-pin power connector.

Any help is appreciated. Thanks, all.

 

[Andy]

fans run. And the computer won't power down unless I unplug it. When I
re-plug, computer turns on instantly WITHOUT power switch, but same symptoms
persist: no POST, no video, fans run, can't turn off with switch, etc.

This is a late-2006 build that has been flawless up to this point. No
warning given.

Asus M2NPV-VM
AMD 64 Athlon X2 3800+
Corsair XMS2 6400 DDR2 512MBx4 (dual mode 800 MHz)
Maxtor Barracuda 250 GB SATA
ATI TV Tuner Card
CD R/W
DVD
Floppy
Linksys Wireless G USB Adapter
USB wireless KB and mouse
Antec Minuet 300 Case with 300W PS
Samsung 23" LCD monitor

Symptoms persist with or without memory, CPU, drives, USB devices or tuner
card connected.

3.3V and 12V power supply rails test OK with multimeter. The (supposedly) 5V
"Power_Good" rail (gray wire on 24-pin connector) tests at 95mV, but I'm not
sure if this is significant with the Antec 300W power supply.

It is significant with all power supplies.
Is the +5V standby power up to specs?

 

[TM]

It is significant with all power supplies.
Is the +5V standby power up to specs?

"> It is significant with all power supplies.

Is the +5V standby power up to specs?"

No it isn't. It measures 95mV. At least I think I'm measuring this in the
right place (grey wire terminal and ground). Where else would you measure 5V
on a 24-pin connector?

I'm negotiating with Antec for an RMA.

 

[Paul]

fans run. And the computer won't power down unless I unplug it. When I
re-plug, computer turns on instantly WITHOUT power switch, but same symptoms
persist: no POST, no video, fans run, can't turn off with switch, etc.

This is a late-2006 build that has been flawless up to this point. No
warning given.

Asus M2NPV-VM
AMD 64 Athlon X2 3800+
Corsair XMS2 6400 DDR2 512MBx4 (dual mode 800 MHz)
Maxtor Barracuda 250 GB SATA
ATI TV Tuner Card
CD R/W
DVD
Floppy
Linksys Wireless G USB Adapter
USB wireless KB and mouse
Antec Minuet 300 Case with 300W PS
Samsung 23" LCD monitor

Symptoms persist with or without memory, CPU, drives, USB devices or tuner
card connected.

3.3V and 12V power supply rails test OK with multimeter. The (supposedly) 5V
"Power_Good" rail (gray wire on 24-pin connector) tests at 95mV, but I'm not
sure if this is significant with the Antec 300W power supply.

Swapped CPU. Still no go.

I've done all of the testing I can think of. I can't swap parts with my
other rig, since it's IDE only and has only 20-pin power connector.

Any help is appreciated. Thanks, all.

Strip out the HDD/CD drives and excess hardware (TV Tuner). Does it post
and can you get into the BIOS ? Simplify as much as possible. Drop
down to one stick of RAM. Etc. Sometimes it is the piece of hardware
you least expect, holding the machine hostage.

When I had the "computer powers up immediately, without pressing the
button" problem, it was caused by a half connected IDE cable. It
got pulled out partially, while I was working inside the machine.
Apparently, if something like that "stresses" the Southbridge and
upsets the circuits on it, it can cause PS_ON# to be asserted
and start up the power. In my case, no damage was done, which
surprised me. I thought my Southbridge would be permanently
toasted by the event.

Paul

 

[TM]

Strip out the HDD/CD drives and excess hardware (TV Tuner). Does it post
and can you get into the BIOS ? Simplify as much as possible. Drop
down to one stick of RAM. Etc. Sometimes it is the piece of hardware
you least expect, holding the machine hostage.

When I had the "computer powers up immediately, without pressing the
button" problem, it was caused by a half connected IDE cable. It
got pulled out partially, while I was working inside the machine.
Apparently, if something like that "stresses" the Southbridge and
upsets the circuits on it, it can cause PS_ON# to be asserted
and start up the power. In my case, no damage was done, which
surprised me. I thought my Southbridge would be permanently
toasted by the event.

Paul

Still no POST. No beeps. No BIOS. With or without IDE drives, memory, etc.

I'm RMAing the case (PS) AND the motherboard. I "paid" for a 3-year
manufacturer's warranty on this stuff, so instead of just willy-nilly buying
new stuff (like I usually do), I'll let them sort it all out.

So long as my backup rig keeps chugging....I'll wait 'em out.