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#1
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Strange power-up problem
I have a GA-7VT880-L motherboard. (Socket A CPU with VIA KT880
chipset). Recently it has developed a strange problem when powering up: Press the power button, and you can hear the power-up sequence starting (CPU & PSU fans start, disks begin to spin up). After about 2 seconds, it just shuts down again. After that, pressing the power button does nothing at all - the system is completely dead. However, if I then switch off the PSU (it has an on/off switch), wait a while, then switch it back on, the system will usually power up successfully and can then be used fine. (Sometimes I may need to do the PSU on/off cycle more than once). I replaced the power supply and the problem persists, so I'm guessing it's some kind of motherboard issue. The question is, does this sound familiar to anyone and if so is there anything I can do about it? Or do I just live with it until the time comes when it bothers me enough to replace the mobo? |
#2
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Strange power-up problem
Clive Backham wrote:
I have a GA-7VT880-L motherboard. (Socket A CPU with VIA KT880 chipset). Recently it has developed a strange problem when powering up: Press the power button, and you can hear the power-up sequence starting (CPU & PSU fans start, disks begin to spin up). After about 2 seconds, it just shuts down again. After that, pressing the power button does nothing at all - the system is completely dead. However, if I then switch off the PSU (it has an on/off switch), wait a while, then switch it back on, the system will usually power up successfully and can then be used fine. (Sometimes I may need to do the PSU on/off cycle more than once). I replaced the power supply and the problem persists, so I'm guessing it's some kind of motherboard issue. The question is, does this sound familiar to anyone and if so is there anything I can do about it? Or do I just live with it until the time comes when it bothers me enough to replace the mobo? Sounds like there may be some defective electrolytic capacitors on the MB. Usually the tall ones near the CPU socket, but they can be anywhere on the MB. Take a look at this web site; it will show pictures of bad caps. They're generally easy to spot: the top may be bulging up, there may be a brown colored material on the top, side, or bottom of a bad cap. http://www.capacitorlab.com/visible-failures/index.htm If you have bad caps, the best thing to do is get a new MB, unless you're skilled at desoldering and removing the bad caps and installing and soldering the new ones. |
#3
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Strange power-up problem
RobV wrote:
Clive Backham wrote: I have a GA-7VT880-L motherboard. (Socket A CPU with VIA KT880 chipset). Recently it has developed a strange problem when powering up: Press the power button, and you can hear the power-up sequence starting (CPU & PSU fans start, disks begin to spin up). After about 2 seconds, it just shuts down again. After that, pressing the power button does nothing at all - the system is completely dead. However, if I then switch off the PSU (it has an on/off switch), wait a while, then switch it back on, the system will usually power up successfully and can then be used fine. (Sometimes I may need to do the PSU on/off cycle more than once). I replaced the power supply and the problem persists, so I'm guessing it's some kind of motherboard issue. The question is, does this sound familiar to anyone and if so is there anything I can do about it? Or do I just live with it until the time comes when it bothers me enough to replace the mobo? Sounds like there may be some defective electrolytic capacitors on the MB. Usually the tall ones near the CPU socket, but they can be anywhere on the MB. Take a look at this web site; it will show pictures of bad caps. They're generally easy to spot: the top may be bulging up, there may be a brown colored material on the top, side, or bottom of a bad cap. http://www.capacitorlab.com/visible-failures/index.htm If you have bad caps, the best thing to do is get a new MB, unless you're skilled at desoldering and removing the bad caps and installing and soldering the new ones. The only comment I'd add, is the symptoms are showing "latch-off". The computer is not recovering from the failure condition, until the switch on the power supply is toggled to OFF and then ON again. That clears the latched failure. A latching failure can occur on some Vcore switching regulator designs (as RobV has observed). And some power supplies can also do that (after an internal failure condition is detected, they won't run until the power is toggled). Since the power supply has been replaced, that leaves the motherboard. Paul |
#4
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Strange power-up problem
Thanks to all who have replied. I've taken a look at the mobo and
don't see any obvious visible signs of a failed capacitor, but I know that electrolytics can still look fine after they've gone bad. I think I'll just live with it for a while until it gets too irritating, then get a more modern mobo and CPU. |
#5
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Strange power-up problem
Funnily enough mine is doing the same thing and it is brand new. The board
is a GA X48T DQ6. If i leave the computer for a period of time it goes into sleep mode (i think). I have set the bios to wake up the pc with a left click of the mouse button, but when i try to awake the pc it just cycles the power up on and off. The only way to prevent this with my limited knowledge is to just set up the power management in control panel to be always on. Phil. "Paul" wrote in message ... RobV wrote: Clive Backham wrote: I have a GA-7VT880-L motherboard. (Socket A CPU with VIA KT880 chipset). Recently it has developed a strange problem when powering up: Press the power button, and you can hear the power-up sequence starting (CPU & PSU fans start, disks begin to spin up). After about 2 seconds, it just shuts down again. After that, pressing the power button does nothing at all - the system is completely dead. However, if I then switch off the PSU (it has an on/off switch), wait a while, then switch it back on, the system will usually power up successfully and can then be used fine. (Sometimes I may need to do the PSU on/off cycle more than once). I replaced the power supply and the problem persists, so I'm guessing it's some kind of motherboard issue. The question is, does this sound familiar to anyone and if so is there anything I can do about it? Or do I just live with it until the time comes when it bothers me enough to replace the mobo? Sounds like there may be some defective electrolytic capacitors on the MB. Usually the tall ones near the CPU socket, but they can be anywhere on the MB. Take a look at this web site; it will show pictures of bad caps. They're generally easy to spot: the top may be bulging up, there may be a brown colored material on the top, side, or bottom of a bad cap. http://www.capacitorlab.com/visible-failures/index.htm If you have bad caps, the best thing to do is get a new MB, unless you're skilled at desoldering and removing the bad caps and installing and soldering the new ones. The only comment I'd add, is the symptoms are showing "latch-off". The computer is not recovering from the failure condition, until the switch on the power supply is toggled to OFF and then ON again. That clears the latched failure. A latching failure can occur on some Vcore switching regulator designs (as RobV has observed). And some power supplies can also do that (after an internal failure condition is detected, they won't run until the power is toggled). Since the power supply has been replaced, that leaves the motherboard. Paul |
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