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**Paul**

wrote:
On Sat, 20 Nov 2010 17:25:21 -0500, 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?
\

Well, here I am back again, dealing with all this. I am sorry I did
not get back sooner, but my wife needs a lot of my care these days
and that keeps me busy.

Where I left it was - I changed to a closet-psu I had and the mobo
still did not fire up - no cpu fan - no video - no beeps. I worried
that this second psu did not have a second 2x2. You suggested I try
booting up without DDRs in place, so I thought I would try that.
I was flabbergasted and embarrassed to discover that one DDR was
dislodged because my removal of the psu cause me to do that.
Naturally, when I re-seated that DDR, the machine booted up fine -
with video.

Again, I am embarrassed. Anyway, I guess this proves that the problem
is the original psu. I am now running with one 2x2 short. What is
that costing me? Should I just go with that, or should I buy the
right psu that fits the mobo?

Thanks again

Duke

What counts in debugging hardware, is whether you fixed it or not.

You succeeded.

*******

With regard to the PSU in your closet, it would depend on whether
you think the electrical load of the computer, can be met by the
power supply. The power supply has a label on the side. Every parameter
oh there means something. Each voltage at current level is specified.
Combined loads are specified (like no more than 100W on 3.3V and 5V).
All the info is useful.

(I'd want all these numbers.)
http://images17.newegg.com/is/image/newegg/17-182-006-S04?$S640W$

Then, you have to look at the hardware. If you provide a complete
hardware inventory, I can give you some idea what it needs.

I allocate 50W, to cover chipset and DIMMs, and that usually covers
what's on the motherboard. it's pretty hard to be more precise than
that with the motherboard, because the parts don't all have datasheets
for download (they're covered by NDA).

The Phenom 9950 comes in 125W and 140W editions. Considering the nature
of the power connector you're using, I'll assume you actually have
the 125W processor. That is about 12V @ 11.5 amps (at 90% Vcore
efficiency). On a dual rail supply, that would be coming from V2.

Your 12V1 load, would depend on the video card. If you're using
integrated video (780V, video connector on the I/O connector
area), then your 12V1 is HDD+ODD+fans or 0.6A+1.5A+0.5A or 2.6A
total. Your total 12V is then 11.5+2.6=14.1 amps. A 12V @ 15A
single rail older supply, covers that on paper, but could use a
bit more margin.

If you have a midrange video card, that might be 12V @ 4A for example,
of extra loading. That brings 12V2 up to 6.6 A.

There were some pretty strong, single rail 12V supplies in the past,
so your older PSU might in fact meet loads like that. If it is a
300W supply from some lightweight computer, then it really is
going to depend on the video card you're using, as to whether
it is enough.

So, a picture or link to the power supply label, plus a list of
the hardware that draws the power, and I can give some answers.

There are also power supply calculator web sites, that will give you
an answer. The worst of those sites, will give a number which is
double the correct answer.

Paul