GA-Z77M-D3H starts, then stops

[pfrcom]

Thinking it might be a BIOS problem, I bought this from an ethics-deficient person who described it as starts but won't POST

Well, it does start but turns off after about one revolution of the CPU and power supply fans

Is this a problem anyone is familiar with fixing?

If so, hand-holding please

[BigTroll]

There are others that probably know more that me but I want to throw this out there. if the board was working fine before it could be weak caps despite being all solid. My zotac h67 1155 board will turn on 1 sec fan spin then off and over and over, however if I put a space heater infront of the board and warm it up for about 10 minutes I will start every-time after that.

Just a suggestion to try.

[ChaosLegionnaire]

thats not a cap problem. thats a problem with bad bga solder joints.

[piernov]

Does it stay on with the P4 CPU power connector disconnected?

[pfrcom]

Originally Posted by piernov

Does it stay on with the P4 CPU power connector disconnected?

It does not - exhibits same behaviour, whether 12V ATX is connected or not

All testing done with a G630 in the socket

[momaka]

Try forcing the motherboard on by shorting the PS_ON signal to ground directly on the PSU's connector (keep the PS_ON shorted the whole time). Do this once with the 4-pin CPU power connector unplugged and again with it plugged in. Does the PSU turn On and shut down or does it stay On. If it shuts down, you likely have a short-circuit somewhere on the board. If it doesn't shut down and runs okay, try pressing the power button on the motherboard/PC case (with the PS_ON still jumpered to ground on the PSU connector.) Does the PSU continue to work or does it shut down. If it continues to run, then likely there aren't any shorted components, at least. In which case, I suggest inspecting the CPU socket carefully for bent pins, and also trying to flex the motherboard around the CPU socket and chipsets while trying to power on - it could be bad BGA. Also check if the ethernet chip is getting hot or not. And try re-seating the RAM several times, as well as trying different sticks (and preferably only 1 or 2 sticks at a time, max).

[pfrcom]

Originally Posted by momaka

Try forcing the motherboard on by shorting the PS_ON signal to ground directly on the PSU's connector (keep the PS_ON shorted the whole time). Do this once with the 4-pin CPU power connector unplugged and again with it plugged in. Does the PSU turn On and shut down or does it stay On.

With PS_ON shorted to GND (bit of thin solder wire bridging Green & Black on ATX connector):

PSU stays On, regardless whether 4-pin connected

When 4-pin connected:

Three keyboard LEDs light briefly

CPU fan races, then slows down - giving impression it's going to POST

Originally Posted by momaka

If it doesn't shut down and runs okay, try pressing the power button on the motherboard/PC case (with the PS_ON still jumpered to ground on the PSU connector.) Does the PSU continue to work or does it shut down.

Doesn't shut down if I short PW+ & PW- on Front Panel Header (testing board on wooden surface, connected to PSU having its own On/Off switch)

And still works the same way if I jumper PW+ & PW- before switching power on

Originally Posted by momaka

I suggest inspecting the CPU socket carefully for bent pins

They look good to me - and I tried cleaning socket & pins by squirting with IPA before reinstalling CPU (G645 this time instead of G630, with different HSF)

Originally Posted by momaka

also trying to flex the motherboard around the CPU socket and chipsets while trying to power on - it could be bad BGA. Also check if the ethernet chip is getting hot or not. And try re-seating the RAM several times, as well as trying different sticks (and preferably only 1 or 2 sticks at a time, max).

Atheros IC feels normal, as does VIA codec and ITE Super IO

Although did have some power glitches when I was feeling around that area, but couldn't reproduce symptoms readily

Still a work-in-progress - at least didn't release the magic smoke with shorted PS_ON & GND

[momaka]

Originally Posted by pfrcom

With PS_ON shorted to GND (bit of thin solder wire bridging Green & Black on ATX connector):

PSU stays On, regardless whether 4-pin connected

When 4-pin connected:

Three keyboard LEDs light briefly

CPU fan races, then slows down - giving impression it's going to POST

That means issue is not a bad/shorted MOSFET.
And depending on how the motherboard is configured for POST, the blinking of they keyboard LEDs could mean all power rails are up and running properly.

Originally Posted by pfrcom

Doesn't shut down if I short PW+ & PW- on Front Panel Header (testing board on wooden surface, connected to PSU having its own On/Off switch)

Right. As long as your manually shorting the PSU's PS_ON signal, the motherboard won't turn off from the power switch.

Originally Posted by pfrcom

And still works the same way if I jumper PW+ & PW- before switching power on

So that rules out the power-up circuitry too.

Originally Posted by pfrcom

They look good to me - and I tried cleaning socket & pins by squirting with IPA before reinstalling CPU (G645 this time instead of G630, with different HSF)

Try flexing the motherboard around the CPU socket then. Have the motherboard flat and do the flexing with and without tightening the CPU heatsink (this can be a bit tricky, so be careful).
Try the same with the chipset heatsink too (but do *not* try it with the heatsink unmounted/loose from the board.)

Originally Posted by pfrcom

Still a work-in-progress - at least didn't release the magic smoke with shorted PS_ON & GND

No, of course it won't.
... not unless you have a really high-power PSU and a partially-shorted MOSFET. Then things can get a bit more "interesting". - Seen that on a high-end graphics card. Some of the MLCCs on the card literally zapped and sparked like firecrackers. PSU was a 1 kW behemoth, though, with no or very high 12V rail limits. So that's why it didn't shut down and kept going.

[pfrcom]

Thanks everyone, especially Momaka, for trying to help

Have tried the flexing a bit, albeit with trepidation

No success, so, have scrapped the board

[momaka]

Sorry to hear that it still didn't work. But I guess that's just luck sometimes. :\