Difficult to explain (sorta) computer problem

[Heywould3]

Hey guys. (long time)

I am stumped on a computer problem that I just cant seem to work out. The problem is that I can not get my old computer to turn on with the power button the normal way. It does work but I have to first hold it down for the 4 second (instant on bios setting set to 4 seconds) once ive done that I can press it again and it will power up.

Something else, if I unplug the power and let the capacitors drain then plug back in the power will work the first time. if I boot up then shut down i can not press the power button again unless I do that trick I mentioned.

I have reset BIOS. I have even flashed the bios to latest version. I have verified that the battery is ok. the BIOS settings all stay set in doing the 4 second hold trick so its not the BIOS, as far as I can tell.

I tried a new power supply and same issue. I have removed the board and set it up on the deck with only minimal components to try to trouble shoot, same thing.

Last thing is that if boot then use sleep mode (not hibernate) the button will work normally to wake it.


Any ideas?

[Heywould3]

I forgot to mention that there are 2 buttons on the board itself a reset and power (like the newer boards) these buttons act the same as the power button on the case. So its not the switch

[aedipuss]

does it do anything if you press the power button normally, or how about moving the mouse? almost sounds like it's asleep/hibernating rather than off.

[Heywould3]

no it does nothing. My power button has a light and when I do a real shut down (not sleep or hibernate) the light will be on, i have to hold it for 4 seconds the button light will turn off, i then know i can release and press it again and it will power up.

Here is the process: I will do a normal shut down within windows (7 pro 64bit) not sleep or hibernate, the thing will power down, the power button light will still be on however, not blinking just steady on. I have to hold it for the 4 seconds and it will wake.

If i use the sleep function the thing will sleep normally and if i press the powerbutton while asleep it will wake normally.

To answer your question, if I press the button once like normal when off it doesnt do anything.

[Heywould3]

Also it did the same thing with windows XP. I just loaded win 7 a few weeks ago... Maybe it is a bios setting? but remember ive flashed it and did the cmos jumper reset

[aedipuss]

what motherboard? there might be a sleep function or something like wake on lan in the power settings that keeps power to the mb.

[Heywould3]

Its a Biostar Tforce 4 r u.

I have the WOL disabled, But I see that you are thinking s bios setting. I just assumed that flashing it would reset to factory settings.

This is a old computer that I gave to my daughter, when it was mine it never did this. i do know that when I built my new one i just had the computer sitting in a closet for a few months, I cant remember exactly what i did when I pulled it out ( in regards to changing hardware or settings) All I know is that once I installed the new HD and loaded the OS it was doing this from the first boot.

[fritzi93]

Very strange.

It put me in mind of a tip I read once quite some time ago about recovering from a bad overclock (and it was useful to me at that time). Clear the CMOS of course, reset to defaults in the BIOS, but here's the point: Unplug the PSU, let the comp sit a while and then hold down the power switch to "discharge" it. It cured some computer weirdness once for me.

Tangential probably, or even irrelevant, I know. Just thought I'd mention it.

[Heywould3]

anything at this point will help, Actually aedipuss got me thinking though, I've been setting the bios to S3 to allow the sleep to work like my current computer, I'm thinking that I should set to S1 and try that..

The comment about the mobo keeping power and the fact that the power switch light stays on even when off.. Acts like its hibernating or sleeping but cant wake due to some compatibility with some hardware in the box

EDIT: S1 didnt change anything, still does the same thing. Oh, worth a shot

[redwudz]

This really sounds like a hardware problem. I would unplug the front panel power switch from the motherboard and try shorting across those 'on' terminals with a screwdriver. That should test to see if the power switch/wiring is the problem. If no change, then I would suspect something with the motherboard.

This method is safe. The MB front panel connections are not directly connected to the PS. They detect when the MB sense terminal is brought low by the power switch (To ground potential). That then sends a signal to a MB transistor switch that sends a low signal to pin 14 or 16 of a ATX power supply connector. (Depends on whether you have a 20 or 24 pin ATX connector.} That then turns on the power supply.

Next step, if you're adventurous, is to use a short jumper to jumper your ATX MB power supply 'on' connector from Pin 14 or 16, depending on whether you have a 20 pin or 24 pin ATX PS connector, to Pin 13 or 15 ground (Black) (Or a nearby ground connector). That will cause your PS to turn on, even without a MB in place. That will rule out the MB if you still have the same delay. Pinouts here: http://pinouts.ru/Power/atxpower_pinout.shtml Make sure you understand the difference between the pinout of your MB and the pinout of your PS with the connector positions. Your MB manual should tell you the correct pins. Be careful. But most PS's are protected by a accidental short circuit.

If none of this helps, then you likely have a motherboard problem. May still be software, but this will rule out most all other hardware problems.

[Heywould3]

Thanks Redwudz, I actually did most of that already. A key indicator here is that the power light on the switch stays on and so does a little LED on the mobo while this problem is present. If I press the power button for the 4 seconds , the switch LED and the mobo LED goes off, I can then press the power again and it will power up normally.

My mobo has a reset and power button soldered right to it, I dont even need to use the power switch on the case. I have actually removed the mobo, set on bench with only video card and required PS connections.