Working theory: Power supply is underserving video card

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I've got an older Pentium 4 system that's been a little crashy.  For a
variety of reasons that I won't bore you with unless you ask, I suspect
that my power supply isn't enough to power my video card.  Here's some
of the hardware involved:


Video Card

TV Tuner

Power Supply

There's also a couple of hard drives, an optical drive, an remote
control sensor and a fan.

What would I need to reasonably supply this system?  Is the video card
primarily going to be drawing off of the 12v rail?  Do I need a supply
with two 12v rails?

Re: Working theory: Power supply is underserving video card

Grinder wrote:
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Isn't that motherboard, for an S754 AMD processor ? The fact that it
stops at 3700+ in the CPU compatibility table, gives me that impression.
If I look an an Athlon 64 3700+ S754 listed here, it runs at 89W. (ADA3700BOX).html

(89W/12V) * (1/0.90) = 8.24 amps to run Vcore for the processor (at 90%

Fans would be 12V @ 0.5 amps. Two hard drives would be 2 * 0.6 amps idling
for the motors. The optical drive might draw 12V @ 1A to 1.5A, but only
when media is present. 8.24+0.5+1.2+1.5 = 11.44 amps of 15 amps available.

Your 9550 might not be using any 12V current.

Now, I'll stop there, after reading the reviews for the supply.

One reviewer for your Rosewill power supply, found leaking capacitors
inside. I think that's all the information we really need :-)
No further analysis about the power rating on the supply is
required. Replace it!

There were some Antec's like that too - some of the Antec ChannelWell
(CWT) contracted supplies had bad caps. You'll get "crashy" as the
caps are about to expire. As long as there is no warranty left on
the Rosewill, undo the screws holding the top cover on the supply, and
inspect for bad caps. Don't touch anything in there -- just look, then
close it back up again.

The bulging tops, and orange-brown leakage, are what you're looking
for. I had four caps in my Antec, with the orange-brown on top. They
were output side caps. It affected the stability of the +5V on the
supply. I got crashing at startup. The day I stopped using my supply,
it was still working, so I didn't use it until it failed entirely.

I wouldn't run the computer on that supply forever. We don't know
how the Rosewill fails, and whether it fails nicely, or goes
with a bang. There are 92 reviews on the Newegg site, and perhaps
someone who had it fail, can tell us what collateral damage there was.
Try reading the reviews, to see what could happen if it fails.
Sometimes, a reviewer will comment on whether the motherboard or
drives got damaged, when the supply completely failed.


Re: Working theory: Power supply is underserving video card

On 7/15/2010 10:47 PM, Paul wrote:
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Yeah, I should have said: Pentium 4 *era*.  In point of fact, I think
there's even a Sempron in there, but I decided to shoot my mouth off
instead of collecting facts.

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Thanks for those considerations.  I'll probably overbuy anyhow.

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Actually, I can provide a data point on a different Rosewill power
supply.  This one:

It went down and took out the motherboard *and* a hard drive.  I didn't
leave a warning review as it had already been pulled by the time the
unit blew.  Also, when I was speaking to Rosewill, the mere mention of
the model number seemed to be enough for them to immediately offer a
refund.  (Is Rosewill a house brand for Newegg?)

I would really like to find a budget manufacturer that is scrupulous
about cutting features instead of quality to get the price down.  I
don't consider "not blowing up my motherboard" a feature.

In retrospect, recommending that Rosewill supply was a moment of
weakness.  I had gotten used to pretty good deals on Antec power
supplies (less than a dime a watt) but *that* week there was nothing on
even close to my price point.  Since that disastrous build I've stuck to
Antec, laying back some inventory when prices are good.

Any recommendations for a good budget supplier of power supplies?

Thanks again, Paul, for your thoughtful reply.  Where do you find the
time to do this?  Are you a clone?

Re: Working theory: Power supply is underserving video card

Grinder wrote:

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I think the reviews on Newegg are a good way to get some idea
what is good and what is bad. The thing is, many companies
contract out, which means quality can vary from one contracting
exercise to the next. Antec, for example, may contract out a
series of designs to the same company, but then tire of them,
and switch the next year to something else. A few of the
Antec's now are by Delta.

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Typing keeps me out of trouble.


Re: Working theory: Power supply is underserving video card

On 7/15/2010 11:11 PM, Grinder wrote:
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Your setup sounds as if it would work with a smaller PS than you have --
assuming that your PS is really doing what it is supposed to do. The 9550
video card is so low power that it is available with passive cooling and
the CPU probably uses 90W or less. Tuner and a couple of hard drives aren't
even worth figuring for power consumption. For comparison my most recent
desktop build has an i7 (147W) and an ATI 5770 which is a double wide with
1gB. All of this plus drives, fans, etc runs easily with at Shuttle 300W PS.

That said, replacing a PS is seldom expensive and often fixes mysterious
problems so I wouldn't hesitate to do it as a troubleshooting step if
everything else has been examined. I've had great luck over the years with
Seasonic power supplies but everyone has their favorite. I certainly
wouldn't spring for one of the expensive gamer-centric units -- too much
money for a little extra performance and a name.

Just my $0.02 of course...

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