-=PCTechTalk=- Re: Start Problem?

CJ,
    In addition to the 4 pin PS to mainboard supply connection, there should 
be another 20 or 24 pin cable going to the mainboard.  Did you try reseating 
that one, too?  Your tester results look fine, but Speedfan is showing some 
oddities.  Since it's a software utility, it doesn't have the ability to 
measure these items directly, so I'm severely discounting those 
measurements.

    Your momentary-type power switch plugs directly into the mainboard, 
which then communicates an 'On' or 'Off' signal to the PS.  The brief 
contact made within the switch is not the same signal that's sent to the PS, 
though.  Instead, the PS doesn't spring into action until the mainboard says 
so.  In order for this to work, the mainboard must have at least some power 
going to it even when powered off.  Some boards even have a small LED to 
indicate that it is receiving juice from the PS.  Since the two signals are 
not the same, it makes sense that there is some sort of translation going on 
within the mainboard's circuitry.  If something should go bad with that part 
of the board, you can get these types of symptoms although the board can 
otherwise perform flawlessly.  As a result, I am suspecting the mainboard of 
having a problem with this part of itself.

    To completely eliminate the switch from the equation, unplug the switch 
connectors from the mainboard header (the mainboard's row of pins that 
accept the front panel lights and such).  Then, use a flat blade screwdriver 
to touch both of the power switch pins at the same time.  You only need to 
connect them for less than a second and the system should spring to life. 
You also have to guard against touching ANY of the other pins to prevent the 
chance of shorting out the board.  If it responds to this exercise without 
any issues, replace both the switch AND the wires connecting it to the board 
(they are usually sold as a unit anyway).  If you still have the same 
issues, then the switch is not the problem at all.  Since you have already 
directly tested the PS, that again leaves the mainboard's PS signal circuit 
as the only remaining suspect.

Peace,
G

"The only dumb questions are the ones that are never asked"

----- Original Message ----- 
From: "cajun12" <cajun12@xxxxxxx>
To: <pctechtalk@xxxxxxxxxxxxx>
Sent: Monday, June 02, 2008 10:11 PM
Subject: -=PCTechTalk=- Start Problem?


> 3-year old home build, Gigabyte 8I915P Duo Pro Motherboard, P4 3.0GHz, =
> 2GB DDR RAM (abt. 1 to 1-1/2 years old), Antec 430 Watt True Power 2.0 =
> PSU (2 years old), Windows XP Home, no errors in Device Manager.  I have =
> not added any peripherals or taken any out in a long time. =20
>
> About 3 weeks ago I started having problems with my computer not wanting =
> to turn on at all.  I've been having to press the Power button over and =
> over, feeling around each side to see what the sweet spot of the day =
> might be, dreading that today would be the day it wouldn't turn on at =
> all.  I cleaned it out, reseated everything, no change. After you press =
> it over and over, it'll come on and run fine.  It's not unstable, not =
> overheating, temps are the same as always, and it's not rebooting =
> itself.  It runs fine until I turn it off for the night.  I thought =
> surely it must be the case power switch.  Everything, including front =
> panel, is attached to the front bezel/face plate.  Hubby is =
> electronically/mechanically inclined and he looked at it, found one =
> broken off out of two naked wires coming off the switch into a small =
> white box that has wires that plug into the HD line to make the light =
> blink when there's HD activity.  He clipped the other naked wire to the =
> same length and shoved them back in the white box and we thought that =
> was surely it - NOT!  I pulled the switch wires off the motherboard to =
> check for dust or loose connections, no change.  Hubby also thought it =
> was the switch, so I bought another case and transferred everything into =
> it, and it's still doing the same thing.  Now I really like my new case =
> and I don't regret buying it, but that's not the problem.
>
> I've reseated the RAM, tried it with just one stick, swapped out the =
> current RAM for the sticks of 512MB Corsair that I upgraded from - no =
> change.  I unplugged all the drives - no change.  I thought maybe one of =
> my optical drives was causing a problem, so I unplugged them one at a =
> time, and plugged them back in one at a time - no change.  A few times =
> we saw the rear fan give a slight jerk when we pressed the power button, =
> but it didn't come on.  I have a brand new LCD power supply tester and =
> the Antec PSU test numbers are below.  The PSU plugs into the MB with a =
> 4-pin 12v connector, which I also plugged into the tester.
>
> +5v:  5.2
> +12v1:  12.1
> +3.3v:  3.3
> -12v:  11.9
> +12v2:  12.0
> 5vSB:  5.2
> PG:  350MS
>
> Here's what Speed Fan shows:
>
> Vcore1:  1.31V
> Vcore2:  2.56V
> +3.3V:  3.23V
> +5V:  4.97V
> +12V:  11.84V
> -12V:  -8.91V
> -5V:  -7.72V
> +5V:  6.85V
> Vbat:  3.18V
>
> So, what else should I be looking at here?  Motherboard?  CPU?  Is it =
> possible to have a circuitry problem on the MB where the Power Switch =
> plugs in?  I've taken in a couple of computers that had motherboard or =
> CPU problems, but they were always unstable and never acted like this.
>
> I'm tired of thinking about it and I need some fresh input.  Thanks!  : =
> )
>
> dj 


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