Fearing my motherboard is toast--any ideas?

[mraloof]

I decided to switch out my power supply (450W) with a new Rosewill
RP550S-2MK (550V)
(link:http://rosewill.com/product/product.aspx?productId=378). The
Rosewill comes with no manuals at all and I figured I'd just connect
the components that need power and connect the motherboard (A-Bit IC7-G
Intel Pentium 4
link:http://abit-usa.com/products/mb/products.php?categories=1&model=4)
with whatever plugs fit. I made a mistake though. The Rosewill comes
with a 20/24 pin power plug for the motherboard and I actually ended up
plugging in the extra four pin plug into the motherboard's ATX 12V
socket thinking that's what it was for.

The machine wouldn't start when it was connected this way though so I
kept trying to figure out what was wrong. Eventually, I realized the
PSU had come with a separate 4pin cable for the ATX 12V socket. I
plugged that in and unplugged the extra 4pin plug and the machine
finally powered on. Joy.

I headed back to my desk, plugged everything in (USB, keyboard, mouse,
monitor, LAN cable, etc.) and powered it on. Everything seemed to start
up just fine but it was shortlived. My monitor stays stuck in what
seems to be a power-save mode now and I can't get it to display
anything. I tried a different monitor and got the same problem. The
machine is whirring away, all fans are on, hard drive's making it's
noise and seems to be working but I can't get any output on the
display. The video card's fan is on (it's an ATI All-In-Wonder 9800
AGP) also.

I ended up trying my old power supply and it now yields the same
results. Everything seems to turn on but my monitor's stay in a
power-save mode of sorts.

Does anyone have any ideas as to what could be wrong? Is it possible I
somehow hosed the motherboard when I had it incorrectly connected to
the power supply? Any ideas or pointers on what I could try or look
into would be greatly appreciated. Thanks in advance!

 

[Peter]

the 20 24 pin is for the main connector depending on what mobo plug u have .
The stand alone 4 pin is for the seperate processor plug on the mobo idont
know what the pin outs but u can find them online. maybe u dint plug your
video card in right or you need to reset the cmos removing the power and
resetting. gl

 

[DaveW]

Sorry to say that you fried your motherboard.

 

[aloof]

Hmm, that's a downer assuming you're not kidding (I don't think you
are). Can you help me understand what action you think did it though so
I at least learn something out of this experience? Was it just trying
to start it with the 4pin connector in the wrong connector?

Thanks all...

 

[aloof]

Also, one more question. Is it safe for me to just focus on replacing
the motherboard and try to salvage everything else (memory, video card,
drives, etc.)? I ask for two reasons: not sure if you think this fried
my processor as well and I can't figure out how to verify that with the
equipment I have and, second, I'm not sure how easy it is to get a
replacement motherboard that works with all the other parts I have as
it's all a few years old now.

Thanks again.

 

[Rod Speed]

Thats overstating the certainty of that.

Hmm, that's a downer assuming you're not kidding (I don't think you are).

No he isnt. But he may be overstating the certainty that the motherboard is dead.

Can you help me understand what action you think did it
though so I at least learn something out of this experience?

The extra 4 pins that you snapped off the 24 pin connector has
different voltages on it than the separate 4 pin square connector.

The separate 4 pin square connector has 2 12V lines and 2 ground lines.

The extra 4 pins you snapped off the 24 pin
connector has 12V, 5V, 3.3V and ground.

Was it just trying to start it with the 4pin connector in the wrong connector?
Yes.

Also, one more question. Is it safe for me to just
focus on replacing the motherboard and try to salvage
everything else (memory, video card, drives, etc.)?

Yes, that should work fine, and it it doesnt, you can replace
the extra bits that got fried in the process later in the unlikely
event that anything else got fried as well as the motherboard.

I ask for two reasons: not sure if you think this fried my processor as well

Its very rare to fry the cpu that way. Its powered from the 12V
rails in current systems and you wont have over voltaged those
and even if you did manage to get the power supply to do that,
that still shouldnt have killed the cpu because its regulated from
that to the Vcore voltage that the cpu sees by the motherboard.

and I can't figure out how to verify that with the equipment I have

The simplest way to do that is just try a new motherboard
and move everything from the old one to the new one.

and, second, I'm not sure how easy it is to get a
replacement motherboard that works with all the
other parts I have as it's all a few years old now.

You should be able to find one that can use the components you have.

 

[aloof]

Thanks Rod! That was very helpful. I ended up buying a new machine (so
there was a bright side) and am now going to find a motherboard that
would work with the old system with hope to salvage it as a server or
something. I appreciate the help though. Thanks all.