wrote:
This was my original post in m.p.w.b. Since I now think my problem is
hardware, namely my PSU, I am continuing my thread here.

I am, and have been for some time, running XP SP3. Have had no
trouble until now. It is on a M3A78_CM mobo with a AMD Phenom 9950
Quad cpu and 4GB DDR2.

I find that it freezes up after being on sometimes an hour, sometimes
longer, requiring re-powering up. I have tried the RAM one at a time,
and I have changed hard drives. Same result.

So I figure it is the CPU or MOBO.


The machine now sits dead - with only a C hard drive. Its mobo has
special power connections, which I cannot match with the few PSUs I
have in the closet. The connections are the normal power plug plus
two square connectors one that is beside the main power connector. the
other a connector elsewhere on the mobo. I have a PSU that has the
normal connector plus one square. I find that it fires up the cpu fan
fine (progress!) but I get no video and no beep or beeps whatsoever,

So, my question is - should I buy a replacement PSU with the correct
connectors?

Thanks

Duke

It's got an ATX12V 2x2 connector (two yellow wires, two black wires).
That connector powers the processor alone. It doesn't power the fan.
On a dual rail supply, that's called "12V2".

The main 24 pin connector, powers the fan headers, and the motherboard
logic. The 12V yellow wire(s) on that connector, run from "12V1". The
hard drives run from 12V1 as well.

(ATX12V can be seen here, in the lower left hand corner of this photo.
The main 24 pin connector is on the upper left. Something must be plugged
into both of those. Make sure the 2x2 connector has two yellow wires,
two black wires, and the plastic latches line up.)

http://images17.newegg.com/is/image/newegg/13-131-330-S03?$S640W$

You can plug in, and use, a 20 pin ATX power supply, into the 24 pin
connector. Pictures of doing so, are shown on this page.

http://www.playtool.com/pages/psucon...onnectors.html

(Using a 20 pin, on a 24 pin motherboard is shown here.
Align the latches. The only time this solution is not advisable,
is if two 6600 type video cards are plugged into the motherboard.
If you have only one video card, then this solution is definitely
OK to use. The two 6600 video card case, causes an 8 amp load on the
main power connector, which is too much for a 20 pin connector.
Even monster video cards don't draw that kind of current any more,
from the slot - they draw more current from the video card separate
connectors. And that's why this option is safe, with only a few
exceptions, and those exceptions involve at least two video cards.)

http://www.playtool.com/pages/psuconnectors/20in24.jpg

Some 24 pin connectors, split in two pieces. This is termed a
20+4 connector. Be careful with this. The 4 pin section has
four *different* color wires, and should not be confused with
the ATX12V 2x2 which has two yellow wires and two black wires.
Only the connector with two yellow wires and two black wires,
goes into the 2x2 motherboard connector. You can do all sorts
of damage, by plugging the other one with the four different
color wires, into that one.

The 20+4 has a "rib" that helps the two sections stay together
when they're plugged into a 24 pin connector. If you wanted,
you can even split a 20+4, and only plug the 20 pin part,
into the 24 pin motherboard. But doing that is pointless. If
you have a 20+4, might as well use all the pins. The four
pin section with the four different color wires, isn't good
for anything else.

If you know, for a fact, your spare power supplies are
good, then you might conclude the motherboard or processor
are bad. But be careful with that assumption. I've got a
couple "ripe Antec supplies" here, with bad capacitors inside.
They'll fail, even if you store the supply in a closet and
don't stress it. The Antecs made by Channelwell, are failing
even when you don't use them. So beware if you're using one
of those. The second one of mine, when I tested it the other
day, was making "a smell", and I can tell it won't be long
before it's gone completely.

One test you can try, is pull all memory DIMMs. Make sure the
computer case speaker, is connected to the PANEL header. If
the computer beeps a repetitive beep pattern at power up,
that means the processor is reading BIOS code. If the
motherboard never, ever makes a beep, then that means
the processor is not currently reading BIOS code. Even
a corrupted BIOS could do that, but in your description,
you don't mention any recent attempts to flash update the
BIOS.

Paul