Single-rail vs. multi-rail power supplies?

On 24/03/2012 3:37 AM, larry moe 'n curly wrote:
Bit-Tech.net says the 1GB Radeon 6870 uses from 128W - 247W. Power
estimators aren't very good and usually give numbers that are way too
high, and when XbitLabs.com took actual measurements, they got this
(associated article goes into much more detail):

http://www.xbitlabs.com/images/coole...attage/p40.png

I don't think the video is at issue at all, it's plugged into its own
private rail, and I've never had any problems with it. It's the storage
units that are having the problems.

Yousuf Khan

On 24/03/2012 12:05 AM, Charlie wrote:
I did not raise the voltage back to where it was. Just enough to stop
the errors. I'm not saying that your errors are caused by the same thing
as mine. Just giving you something else to try.

Well, I'll keep it in mind then. When all else fails, that's worth a
shot. But of course my first solution is a new PS.

Yousuf Khan

On 24/03/2012 9:16 AM, Arno wrote:
Ah, so you have a _theoretical_ result indicating possible errors.
In that case you may want to redistribute your deicves a bit to
the other rails, not replace the PSU. But note that typically,
with a good quality PSU, 15% more load on one rail should not be
an issue, as long as it is not permanent load and the device is
overall not overloaded. You should also have had some overestimation
in that calculation if you did it right.

I would, if I could, but I don't think there's any way to redistribute
them. Certain rails are dedicated to specific tasks, like motherboard
power, CPU power, and GPU power, and miscellaneous power for everything
else. It's miscellaneous power that is having problems now.

A single rail PS won't have this issue. Either everything will be
underpowered, or nothing will be.

Yousuf Khan

Yousuf Khan wrote
Arno wrote

Ah, so you have a _theoretical_ result indicating possible errors.
In that case you may want to redistribute your deicves a bit to
the other rails, not replace the PSU. But note that typically,
with a good quality PSU, 15% more load on one rail should not be an issue, as long as it is not permanent load and
the device is overall not overloaded. You should also have had some overestimation in that calculation if you did it
right.

I would, if I could, but I don't think there's any way to redistribute
them. Certain rails are dedicated to specific tasks, like motherboard
power, CPU power, and GPU power, and miscellaneous power for
everything else. It's miscellaneous power that is having problems now.

A single rail PS won't have this issue. Either everything will be
underpowered, or nothing will be.

I dont believe there is any evidence that you do have an underpowered rail.

The obvious way to prove wherther you do or not is to calculate the rail
CURRENTS using the datasheet values for the startup currents of the hard drives.

It would be worth trying any power supply you have to hand,
to see if that makes those optical drive errors go away.

You can even get the power supply from one of the operations like egghead
that do allow you to return the supply if you find it makes no difference to the
optical errors if you dont actually have a spare power supply handy or borrowable.

On Wed, 21 Mar 2012 18:30:38 -0400, Paul wrote:





I don't own a copy of IEC60950, so I can't copy/paste
the appropriate part. And the last time I looked, I couldn't
find a copy "floating" on the web. The keyword "SELV" comes
to mind, but that's about all I remember now.

http://www.freetechebooks.com/file-2...60950-pdf.html

Yousuf Khan wrote:

On 24/03/2012 3:37 AM, larry moe 'n curly wrote:

Bit-Tech.net says the 1GB Radeon 6870 uses from 128W - 247W. Power
estimators aren't very good and usually give numbers that are way too
high, and when XbitLabs.com took actual measurements, they got this
(associated article goes into much more detail):

http://www.xbitlabs.com/images/coole...attage/p40.png

I don't think the video is at issue at all, it's plugged into its own
private rail, and I've never had any problems with it. It's the storage
units that are having the problems.

Does the Zalman really have 4 separate rails, which would require at
least 4 separate windings for the +12V rails, or does it just have 4
separate current sense lines? Because JonnyGuru.com has found that
many PSUs advertised as being multirail have all the +12V lines
connected to the same place on the circuit board. Also the video
card probably won't be as sensitive to fluctuations from the +12V
because it has its own voltage regulator. Disk drives do, too, for
some voltages, but I don't know about the +12V for the motors.

On Sun, 25 Mar 2012 03:48:18 -0400, shawn wrote:

On Wed, 21 Mar 2012 18:30:38 -0400, Paul wrote:





I don't own a copy of IEC60950, so I can't copy/paste the appropriate
part. And the last time I looked, I couldn't find a copy "floating" on
the web. The keyword "SELV" comes to mind, but that's about all I
remember now.

http://www.freetechebooks.com/file-2...60950-pdf.html

Nice try, but it's only the first few pages.
IEC doesn't let this one out without paying for it.

Here's some pages that give you the gist of what's in the spec:

http://www.i-spec.com/IEC_60950/iec_60950.html

but to get the detailed requirements, you have to buy the spec.

SELV refers to circuits that are separated physically and electrically
from the other circuits, and do not carry a voltage more than 60V DC, or
42.5V peak AC.

On 25/03/2012 8:02 AM, larry moe 'n curly wrote:
Does the Zalman really have 4 separate rails, which would require at
least 4 separate windings for the +12V rails, or does it just have 4
separate current sense lines? Because JonnyGuru.com has found that
many PSUs advertised as being multirail have all the +12V lines
connected to the same place on the circuit board. Also the video
card probably won't be as sensitive to fluctuations from the +12V
because it has its own voltage regulator. Disk drives do, too, for
some voltages, but I don't know about the +12V for the motors.

I don't know, according to this:

http://www.zalman.com/eng/product/Pr...ad.asp?idx=196

"Four Independent +12VDC Outputs
Four +12VDC rails supply power independently to the CPU, VGA,
motherboard, and peripheral components for the highest level of
stability and performance. "

But that could just be marketing speak.

Yousuf Khan

On 25/03/2012 1:46 PM, Yousuf Khan wrote:
On 25/03/2012 8:02 AM, larry moe 'n curly wrote:
Does the Zalman really have 4 separate rails, which would require at
least 4 separate windings for the +12V rails, or does it just have 4
separate current sense lines? Because JonnyGuru.com has found that
many PSUs advertised as being multirail have all the +12V lines
connected to the same place on the circuit board. Also the video
card probably won't be as sensitive to fluctuations from the +12V
because it has its own voltage regulator. Disk drives do, too, for
some voltages, but I don't know about the +12V for the motors.

I don't know, according to this:

http://www.zalman.com/eng/product/Pr...ad.asp?idx=196

"Four Independent +12VDC Outputs
Four +12VDC rails supply power independently to the CPU, VGA,
motherboard, and peripheral components for the highest level of
stability and performance. "

But that could just be marketing speak.

Yousuf Khan

The following review article seems to doubt that the four rails are
actually independent.

http://www.silentpcreview.com/article688-page1.html

Yousuf Khan

Yousuf Khan wrote:
On 25/03/2012 1:46 PM, Yousuf Khan wrote:
On 25/03/2012 8:02 AM, larry moe 'n curly wrote:
Does the Zalman really have 4 separate rails, which would require at
least 4 separate windings for the +12V rails, or does it just have 4
separate current sense lines? Because JonnyGuru.com has found that
many PSUs advertised as being multirail have all the +12V lines
connected to the same place on the circuit board. Also the video
card probably won't be as sensitive to fluctuations from the +12V
because it has its own voltage regulator. Disk drives do, too, for
some voltages, but I don't know about the +12V for the motors.

I don't know, according to this:

http://www.zalman.com/eng/product/Pr...ad.asp?idx=196

"Four Independent +12VDC Outputs
Four +12VDC rails supply power independently to the CPU, VGA,
motherboard, and peripheral components for the highest level of
stability and performance. "

But that could just be marketing speak.

Yousuf Khan

The following review article seems to doubt that the four rails are
actually independent.

http://www.silentpcreview.com/article688-page1.html

Yousuf Khan

http://www.jonnyguru.com/modules.php...Story2&reid=30

http://www.hardwaresecrets.com/artic...y-Review/402/6

It could be a single transformer with four output windings for +12V.
And four diode pairs (one pair per three legged package) for rectification
on the outputs. There are no closeup shots of the solder blobs on the wire
loom area, to see whether the 12V outputs are joined after the rectifiers
or anything.

The second reviewer, seems to be using a load tester with only two 12V loads
to use for the four outputs. The first reviewer is using a strange
loading pattern, which helps make 12V2 and 12V4 look like they're connected
together (identical voltages).

Paul