ecs k7s5a pro powering itself back on

[rbv24]

I replaced a ECS k7s5a mobo because of a real time clock problem, with a ECS k7s5a pro. The clock issued is resolved but now I am having a problem with the PC powering itself back 10 minutes after a shutdown. The OS is Windows XP Home with SP1. I returned the mobo to the vendor and am still having the same problem with the replacement. I checked the bios settings in the power management section and the option for wake on ring/lan is disabled.

Has anyone else run into this problem? If so what resolved the issue?

Thanks,

 

[Peter]

That happens when the power supply unit is too weak or twitchy on the +5Vstandby rail, or when Keyboard/Mouse/LAN/Modem power on is enabled and the respective peripheral produces line noise on the Wake signal.

 

[pspada]

I had one that was not powering up the hard drive properly on boot. I swapped the power cables leading to the hard drive, and it appears to work fine now. In your case you've pretty much proved it's not the mobo, so it's likely to be the power supply. Or if you are really unlucky, perhaps a more costly part of your system is going bad....

 

[Peter]

pspada, you know that the power supply doesn't switch the individual power cords individually? And the mainboard is nothing to do with this at all. You just got a bad HDD power wire or connector there. Usually that's a bad connector, or a pinched cable. Examine it for the latter - shorts to chassis ground are not funny.

 

[pspada]

it's stranger than that - the machine would sometimes not power on the hard drive on power up, but always powered it up when the reset button is pressed thereafter. Now in the old days, some hard drives were particularly bad at this - if you powered on the monitor at the same time as the machine, they did not get enough power to spin up. But I've never seen this in many years now.

But I did check for shorts, and there are none. But the power supply could just be dying. I'll know if the problem re-occurs in the near future.

 

[Peter]

That'll be a crap PSU then, slow at ramping the power rails.

 

[pspada]

I've used perhaps on the order of 100 of these Raidmax 350w powersupplies. One was bad out of the box, and with this one as a possible exception, all are running great.