motherboard won`t powerdown - K7S8XE+

[SlashEMc2k]

I have had my pc for about a year now working fine until one day the PC would just not shut down? It reboots fine though?

So I upgraded my PSU as other strange things were happening like mouse and keyboard stopped working and had read on these forums the PSU would probably be the first thing that needed replacing.

I have replaced the PSU and now the mouse and keyboard works fine but I still cannot shutdown without switching the PSU off?

When I switch on the PSU the computer automatically turns on and boots through bios into XP.

If I press the power off button during the boot through bios or xp the machine freezes. And does not switch off the computer or load any further?? Really strange.

I have installed a fresh copy of XP just incase, I don`t know why but I just did.. lol.

I have cleared the CLRCMOS2 a few times and resetup the bios but still have the same problem.

I presume the problem lies with the capacitors
I have visually inspected all the electrolytic capacitors and can post pictures but can`t see any bulging or goo comming from any of them..

Does anyone have a good knowledge of the K7S8XE+ and suggest which capacitor to try and test with a multimete and replace if faulty..

Any ideas or help would be appreciated

Machine specs:
Asrock K7S8XE+ V1.61
Athlon XP 2000+
64mb Matrox Millenium G450 Dual Head
256 MB RAM
80GB IDE HD
300 watt PSU
Windows XP Professional

[Per Hansson]

Re: motherboard won`t powerdown - K7S8XE+

Check if the BIOS has a "power on after power fail" setting, change the setting from whatever it is set to, and then back to "off" or "former status"

That might fix it, but more probably not

[MD Willington]

Re: motherboard won`t powerdown - K7S8XE+

Good to see you made it SlashEMc2k...

[SlashEMc2k]

Re: motherboard won`t powerdown - K7S8XE+

Thanks MD; got to try everything before I throw and replace this MB..

Tried Setting Restore on AC/Power Loss on and off but made no difference

[SlashEMc2k]

Re: motherboard won`t powerdown - K7S8XE+

here are images of my caps.
See can`t see any problems
image 1
image 2
image 3
image 4
image 5

[Shroomie]

Re: motherboard won`t powerdown - K7S8XE+

Well, those OSTs will go bad eventually, but they're some of the better bad caps. Look OK for now though...

[Galvanized]

Re: motherboard won`t powerdown - K7S8XE+

You might want to consider what yanz had to say in this thread.

https://www.badcaps.net/forum/showth...6808#post16808

[gonzo0815]

Re: motherboard won`t powerdown - K7S8XE+

Well, i have a K7s8xe+ too and experineced some other problems. I have recaped the vrm & ram caps, but i think this wasn`t necessary. May be i had to replace those smaler caps, but haven`t done it yet.
Those small caps aren`t that speccial, any good will work here. For the other caps only super low esr caps are suitable, as the desing of this board is optimized fo lowest possible component count (therefore it maxed out the specs of the best cpas).
I could immagine, that there is a problem with those smaler caps, which will cause som groundbouncing causing the power on.
Or there is an switch burnt, leding to a permanent short on the pw switch.

In any case, before i would do anything, i would test for and short caused by mounting, screws etc. Then chek the pin assginments of the system header, may be there is something wrong(you can power it up by shorting the pw_sw headers). Test wise you can try to unplug the pw switch and look if the issu is gone.
Additionaly there is an sb power jumper, which will fed the mouse, usb and keybord from the SB line of the psu. may be it will help to disable that.
To ensure cmose is cleared properly, sometimes it is needed to rmove all power, including the cmos battery.
This could easily done by removing the whole board from the case and place it on a isolating surface.
I do this with any system, to make shure it`S the hardware and not something else.
Then , make shure your new psu is capable to deliver AT LEAST 180w better over 200w combined power on the 5v and 3.3v line.
And it should be from a respectable manufakturer too. Anything less will for shure only give you haddaches with this board.
Most new ATX2.0 PSU`S wont power this board for long, as they only have strong 12v rails.