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Power supply requirement for 2 Nvidia GTX in SLI?



 
 
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  #1  
Old March 12th 08, 11:13 AM posted to alt.comp.periphs.videocards.nvidia
huLLy
external usenet poster
 
Posts: 2
Default Power supply requirement for 2 Nvidia GTX in SLI?

OK, my system:

AMD 6400 AM2 Processor
Asus M2N SLi Deluxe Mobo
4 Gig RAM
1 250GB Sata, 2*400GB Sata Drives
2x Nvidia 768M 8800GTX
XFi extreme gamer soundcard

My question is what size PSU will I need to run this lot when gaming?

Will a Hiper 730W do the trick??

--
huLLy
Tel 07976 123278


  #2  
Old March 12th 08, 04:52 PM posted to alt.comp.periphs.videocards.nvidia
Phil Weldon[_2_]
external usenet poster
 
Posts: 131
Default Power supply requirement for 2 Nvidia GTX in SLI?

'huLLy' wrote:
My question is what size PSU will I need to run this lot when gaming? OK,
my system:

AMD 6400 AM2 Processor
Asus M2N SLi Deluxe Mobo
4 Gig RAM
1 250GB Sata, 2*400GB Sata Drives
2x Nvidia 768M 8800GTX
XFi extreme gamer soundcard

My question is what size PSU will I need to run this lot when gaming?

Will a Hiper 730W do the trick??

_____

Never heard of a 'Hipper' brand power supply, but if it is decent and really
is rated at 730 Watts continuous operation, yes, 730 Watts is plenty for
total power; just make sure that the + 12 VDC rails can provide the
necessary current:

CPU: ~ 12 Amperes for the 12 DC-DC down converter-regulator

PLUS

8800 GTX: ~ 12 Amperes Peak Load each (see
http://www.xbitlabs.com/articles/vid...p_6.html#sect0 ) PLUSeach drive, a max of ~ 2 Amperes when spinning up from stopped to fullspeed, ~ 1/2 Ampere otherwise (3 drives plus, I assume an optical drive?)PLUSa few Amperes for everything else.That's a total of 45 Amperes from the +12 VDC rails (there may be from oneto three +12 VDC rails), 540 Watts max. Add 100 Watts or so are from the +5 VDC and +3.3 VDC rails (memory, motherboard, drives,audio card.) Addanother 5 Watts or so for + 5 VDC Standby, perhaps nothing at all for the -12 VDC (the audio card MIGHT use -12 VDC, nothing else will), - 5 VDC is nolonger even provided. The grand total will be under 650Watts (the currentallowances for the CPU, 8800 GTX's, and drives are generous.)The present standard for ATX power supplies is ATX 12V ver. 2.31 (see http://www.formfactors.org/developer...V_1_3dg.pdfand http://www.formfactors.org/developer..._Rev_1_2 .pdf )include 'current sharing' among the +12 VDC rails, the +5 VDC rails, and the+3.3 VDC rails so that much of the unneeded current capacity of the lowervoltage rails can be used by the +12 VDC rails (up to the rated maximum.)HOWEVER, you might feel more comfortable with a good power supply with a 850Watt rating; after all, you are spending more $1000 for your displayadapters, so the incremental cost of going from a 730 Watt to a 850 Wattsupply is a small percentage of the system cost. And, as always, a welldesigned and constructed power supply with a lower rated capacity may outperform a poor quality power supply with a higher rating. (Seehttp://www.xbitlabs.com/ for power supply ratings and reviews.)Phil Weldon"huLLy" wrote in messagenews:ToidnTsWI9R5MUranZ2dnUVZ8qqdnZ2d@gigan ews.com... OK, my system: AMD 6400 AM2 Processor Asus M2N SLi Deluxe Mobo 4 Gig RAM 1 250GB Sata, 2*400GB Sata Drives 2x Nvidia 768M 8800GTX XFi extreme gamer soundcard My question is what size PSU will I need to run this lot when gaming? Will a Hiper 730W do the trick?? -- huLLy Tel 07976 123278
  #3  
Old March 12th 08, 11:41 PM posted to alt.comp.periphs.videocards.nvidia
Paul
external usenet poster
 
Posts: 13,364
Default Power supply requirement for 2 Nvidia GTX in SLI?

huLLy wrote:
OK, my system:

AMD 6400 AM2 Processor
Asus M2N SLi Deluxe Mobo
4 Gig RAM
1 250GB Sata, 2*400GB Sata Drives
2x Nvidia 768M 8800GTX
XFi extreme gamer soundcard

My question is what size PSU will I need to run this lot when gaming?

Will a Hiper 730W do the trick??


I get a total of about 12V @ 37.1A, but it will be spread
across the rails, according to how the output is wired.
Some supplies use a single 12V output, which means not
having to figure out the distribution.

For total power I get (approximately) -

(12*37.1) + 50 + 3*5 + 1*7.5 + 10 = 528W

There is a manual for a 730W supply here.

http://www.hipergroup.com/English/do..._datasheet.pdf

Tracking where the +12V current flows, gives this. The
four PCI Express connectors, are spread one per rail.
That really isn't the best way of distributing the loading,
as the processor load on 12V2 is pretty significant, and
so 12V2 really shouldn't be used for more than the processor.

Video card = 12V_slot + 12V_EXT1 + 12V_EXT2
= 3.67A + 3.58A + 3.42A

Power supply rails, and resulting load distribution (0.5A for
fans, 3.3A for 3 hard drives and 1 optical drive)

PCI-Express 12V1 3.58 = 3.58A
ATX Main + PCI-Express 12V3 3.67 + 3.67 + 0.5 + 3.58 = 11.42A
ATX12V 2x2 + PCI-Express 12V2 12 + 3.42 = 15.42A
Drives + PCI-Express 12V4 3.3A + 3.42 = 6.72A

The Hiper supply could do the job. Or the following
Silencer 750W would also be suitable. This one uses
a single 12V rail, such that the user doesn't have to
worry about how the rail limits, like the ones above,
are policed by the supply.

Silencer 750
http://www.newegg.com/Product/Produc...82E16817341011

Paul
  #4  
Old March 12th 08, 11:51 PM posted to alt.comp.periphs.videocards.nvidia
Mr.E Solved!
external usenet poster
 
Posts: 888
Default Power supply requirement for 2 Nvidia GTX in SLI?

Paul wrote:
huLLy wrote:
OK, my system:

AMD 6400 AM2 Processor
Asus M2N SLi Deluxe Mobo
4 Gig RAM
1 250GB Sata, 2*400GB Sata Drives
2x Nvidia 768M 8800GTX
XFi extreme gamer soundcard

My question is what size PSU will I need to run this lot when gaming?

Will a Hiper 730W do the trick??


I get a total of about 12V @ 37.1A, but it will be spread
across the rails, according to how the output is wired.
Some supplies use a single 12V output, which means not
having to figure out the distribution.

For total power I get (approximately) -

(12*37.1) + 50 + 3*5 + 1*7.5 + 10 = 528W

There is a manual for a 730W supply here.

http://www.hipergroup.com/English/do..._datasheet.pdf


Tracking where the +12V current flows, gives this. The
four PCI Express connectors, are spread one per rail.
That really isn't the best way of distributing the loading,
as the processor load on 12V2 is pretty significant, and
so 12V2 really shouldn't be used for more than the processor.

Video card = 12V_slot + 12V_EXT1 + 12V_EXT2
= 3.67A + 3.58A + 3.42A

Power supply rails, and resulting load distribution (0.5A for
fans, 3.3A for 3 hard drives and 1 optical drive)

PCI-Express 12V1 3.58 = 3.58A
ATX Main + PCI-Express 12V3 3.67 + 3.67 + 0.5 + 3.58 = 11.42A
ATX12V 2x2 + PCI-Express 12V2 12 + 3.42 = 15.42A
Drives + PCI-Express 12V4 3.3A + 3.42 = 6.72A

The Hiper supply could do the job. Or the following
Silencer 750W would also be suitable. This one uses
a single 12V rail, such that the user doesn't have to
worry about how the rail limits, like the ones above,
are policed by the supply.

Silencer 750
http://www.newegg.com/Product/Produc...82E16817341011

Paul


That was nice of you to do all that work for the OP, I hope he
appreciates it.
  #5  
Old March 13th 08, 01:07 AM posted to alt.comp.periphs.videocards.nvidia
Paul
external usenet poster
 
Posts: 13,364
Default Power supply requirement for 2 Nvidia GTX in SLI?

Mr.E Solved! wrote:
Paul wrote:
huLLy wrote:
OK, my system:

AMD 6400 AM2 Processor
Asus M2N SLi Deluxe Mobo
4 Gig RAM
1 250GB Sata, 2*400GB Sata Drives
2x Nvidia 768M 8800GTX
XFi extreme gamer soundcard

My question is what size PSU will I need to run this lot when gaming?

Will a Hiper 730W do the trick??


I get a total of about 12V @ 37.1A, but it will be spread
across the rails, according to how the output is wired.
Some supplies use a single 12V output, which means not
having to figure out the distribution.

For total power I get (approximately) -

(12*37.1) + 50 + 3*5 + 1*7.5 + 10 = 528W

There is a manual for a 730W supply here.

http://www.hipergroup.com/English/do..._datasheet.pdf


Tracking where the +12V current flows, gives this. The
four PCI Express connectors, are spread one per rail.
That really isn't the best way of distributing the loading,
as the processor load on 12V2 is pretty significant, and
so 12V2 really shouldn't be used for more than the processor.

Video card = 12V_slot + 12V_EXT1 + 12V_EXT2
= 3.67A + 3.58A + 3.42A

Power supply rails, and resulting load distribution (0.5A for
fans, 3.3A for 3 hard drives and 1 optical drive)

PCI-Express 12V1 3.58 = 3.58A
ATX Main + PCI-Express 12V3 3.67 + 3.67 + 0.5 + 3.58 = 11.42A
ATX12V 2x2 + PCI-Express 12V2 12 + 3.42 = 15.42A
Drives + PCI-Express 12V4 3.3A + 3.42 = 6.72A

The Hiper supply could do the job. Or the following
Silencer 750W would also be suitable. This one uses
a single 12V rail, such that the user doesn't have to
worry about how the rail limits, like the ones above,
are policed by the supply.

Silencer 750
http://www.newegg.com/Product/Produc...82E16817341011

Paul


That was nice of you to do all that work for the OP, I hope he
appreciates it.


The part that bothers me about these multi-rail supplies, is whether
they'd actually get upset, if the rating printed on the label is
exceeded. That supply is a quad 16 amp, and the 12V2 is getting
pretty close to the limit. Some of the good sites that review
power supplies, find they can double the load on a single rail,
without the supply shutting off. I feel guilty doing the analysis,
like the one I attempted above, when I don't know for a fact that
the supply "tips over" at 16A. But I have to follow what I see on
the label, and pretend that what is printed on the label, is
gospel.

Paul
  #6  
Old March 13th 08, 02:45 AM posted to alt.comp.periphs.videocards.nvidia
First of One[_2_]
external usenet poster
 
Posts: 1,284
Default Power supply requirement for 2 Nvidia GTX in SLI?

As you know, some power supplies made by Seasonic and PCP&C are really
single-rail, but were advertised as multi-rail at one time because it was
fashionable. Now single-rail supplies are trendy, you see all kinds of
monster PSUs re-labeled with 50A or even 70A ratings on the 12V.

--
"War is the continuation of politics by other means.
It can therefore be said that politics is war without
bloodshed while war is politics with bloodshed."

"Paul" wrote in message ...
The part that bothers me about these multi-rail supplies, is whether
they'd actually get upset, if the rating printed on the label is
exceeded. That supply is a quad 16 amp, and the 12V2 is getting
pretty close to the limit. Some of the good sites that review
power supplies, find they can double the load on a single rail,
without the supply shutting off. I feel guilty doing the analysis,
like the one I attempted above, when I don't know for a fact that
the supply "tips over" at 16A. But I have to follow what I see on
the label, and pretend that what is printed on the label, is
gospel.

Paul



  #7  
Old March 13th 08, 04:36 AM posted to alt.comp.periphs.videocards.nvidia
Paul
external usenet poster
 
Posts: 13,364
Default Power supply requirement for 2 Nvidia GTX in SLI?

First of One wrote:
As you know, some power supplies made by Seasonic and PCP&C are really
single-rail, but were advertised as multi-rail at one time because it was
fashionable. Now single-rail supplies are trendy, you see all kinds of
monster PSUs re-labeled with 50A or even 70A ratings on the 12V.


I just wish the industry had some standards for this. It shouldn't boil
down to some review site opening the thing with a screwdriver, to figure
out how it works, and how it can be used.

Paul
  #8  
Old March 13th 08, 04:41 AM posted to alt.comp.periphs.videocards.nvidia
Phil Weldon[_2_]
external usenet poster
 
Posts: 131
Default Power supply requirement for 2 Nvidia GTX in SLI?

'Paul' wrote:
First of One wrote:
As you know, some power supplies made by Seasonic and PCP&C are really
single-rail, but were advertised as multi-rail at one time because it was
fashionable. Now single-rail supplies are trendy, you see all kinds of
monster PSUs re-labeled with 50A or even 70A ratings on the 12V.


I just wish the industry had some standards for this. It shouldn't boil
down to some review site opening the thing with a screwdriver, to figure
out how it works, and how it can be used

_____

There IS a standard; see
http://www.formfactors.org/developer...X12V_1_3dg.pdf
and
http://www.formfactors.org/developer..._Rev_1_2 .pdf )
..

The idea behind the separate current limited + 12 VDC rails is to avoid a
fault condition that can draw 500 or more Watts before safety circuits kick
in.

Phil Weldon

"Paul" wrote in message ...
First of One wrote:
As you know, some power supplies made by Seasonic and PCP&C are really
single-rail, but were advertised as multi-rail at one time because it was
fashionable. Now single-rail supplies are trendy, you see all kinds of
monster PSUs re-labeled with 50A or even 70A ratings on the 12V.


I just wish the industry had some standards for this. It shouldn't boil
down to some review site opening the thing with a screwdriver, to figure
out how it works, and how it can be used.

Paul


  #9  
Old March 13th 08, 05:09 AM posted to alt.comp.periphs.videocards.nvidia
Paul
external usenet poster
 
Posts: 13,364
Default Power supply requirement for 2 Nvidia GTX in SLI?

Phil Weldon wrote:
'Paul' wrote:
First of One wrote:
As you know, some power supplies made by Seasonic and PCP&C are
really single-rail, but were advertised as multi-rail at one time
because it was fashionable. Now single-rail supplies are trendy, you
see all kinds of monster PSUs re-labeled with 50A or even 70A ratings
on the 12V.


I just wish the industry had some standards for this. It shouldn't boil
down to some review site opening the thing with a screwdriver, to figure
out how it works, and how it can be used

_____

There IS a standard; see
http://www.formfactors.org/developer...X12V_1_3dg.pdf
and
http://www.formfactors.org/developer..._Rev_1_2 .pdf
) .

The idea behind the separate current limited + 12 VDC rails is to avoid
a fault condition that can draw 500 or more Watts before safety circuits
kick in.

Phil Weldon

"Paul" wrote in message ...
First of One wrote:
As you know, some power supplies made by Seasonic and PCP&C are
really single-rail, but were advertised as multi-rail at one time
because it was fashionable. Now single-rail supplies are trendy, you
see all kinds of monster PSUs re-labeled with 50A or even 70A ratings
on the 12V.


I just wish the industry had some standards for this. It shouldn't boil
down to some review site opening the thing with a screwdriver, to figure
out how it works, and how it can be used.

Paul



I've heard of the 240VA limit from IEC60950, but it appears to be
optional to support it.

http://www.pcpower.com/technology/myths/

"PC Power and Cooling is once again leading the industry. All of
our power supplies now feature a large, single 12-volt rail. The
design is favored by major processor and graphics companies,
complies with EPS12V specs (the 240VA limit is not a requirement)
and is approved by all major safety agencies such as UL and TUV.3"

I'm not going to argue the merits of that statement, because I don't have
a copy of the appropriate spec that calls up the 240VA limit. I understand
it is traceable to something like 60950, but don't have a copy.

I was referring more to the architecture of the supplies. While formfactors
has a design document for dual rail supplies, I'm not aware of any standard
for tri or quad rail supplies. (Maybe design guidance comes from some
server spec ?) And the assignment of connectors, seems to be largely left
to chance. On the plus side, I am finding more documentation than I used
to. A few years ago, it used to be really frustrating to find out
what the wiring plan was. (Took a review article, to get the story. The
manufacturer couldn't be bothered to list it.)

Paul
  #10  
Old March 13th 08, 02:11 PM posted to alt.comp.periphs.videocards.nvidia
Phil Weldon[_2_]
external usenet poster
 
Posts: 131
Default Power supply requirement for 2 Nvidia GTX in SLI?

'Paul' wrote:

I'm not going to argue the merits of that statement, because I don't have
a copy of the appropriate spec that calls up the 240VA limit. I understand
it is traceable to something like 60950, but don't have a copy.

_____

See

"3.4.4. Over-current Protection
Overload currents applied to each tested output rail will cause the output
to trip before reaching
or exceeding 240 VA. For testing purposes, the overload currents should be
ramped at a
minimum rate of 10 A/s starting from full load."

on page 22 at
http://www.formfactors.org/developer...X12V_1_3dg.pdf .

Notice the phrase 'will cause the output to trip'.

and

8.1 North America - REQUIRED
The power supply must be certified by an NRTL (Nationally Recognized Testing
Laboratory) for use in the USA and Canada under the following conditions:
.. The power supply UL report "Conditions of Acceptability" shall meet in the
intended
application of the power supply in the end product.
.. The supply must be recognized for use in Information Technology Equipment
including Electrical Business Equipment per UL 60950-1 First Edition. The
certification must include external enclosure testing for the AC receptacle
side of
the power supply (see Appendices A, B, C, and D).
.. The supply must have a full complement of tests conducted as part of the
certification, such as input current, leakage current, hi-pot, temperature,
energy
discharge test, transformer output characterization test (open-circuit
voltage,
short-circuit performance), and abnormal testing (to include stalled-fan
tests and
voltage-select-switch mismatch).

on page 45 at

http://www.formfactors.org/developer..._Rev_1_2 .pdf .

And see

"If the selected power supply has any single output rated at more than 240VA
contact with circuits connected to the output must be prevented in user
access areas, protection may be achieved by insulation, guarding or
interlocks (refer to IEC 60950-1 First Edition, 2001 Clauses 0.2.2 and 2.1)"


at

http://www.intel.com/cd/channel/rese.../eng/35831.htm .


And, finally, see 'UL 60950-1 Information Technology', page 80

at

http://www.psui.com/1upower/pdf/901_ref.pdf .

Phil Weldon



"Paul" wrote in message ...
Phil Weldon wrote:
'Paul' wrote:
First of One wrote:
As you know, some power supplies made by Seasonic and PCP&C are really
single-rail, but were advertised as multi-rail at one time because it
was fashionable. Now single-rail supplies are trendy, you see all kinds
of monster PSUs re-labeled with 50A or even 70A ratings on the 12V.


I just wish the industry had some standards for this. It shouldn't boil
down to some review site opening the thing with a screwdriver, to figure
out how it works, and how it can be used

_____

There IS a standard; see
http://www.formfactors.org/developer...X12V_1_3dg.pdf
and
http://www.formfactors.org/developer..._Rev_1_2 .pdf )
.

The idea behind the separate current limited + 12 VDC rails is to avoid a
fault condition that can draw 500 or more Watts before safety circuits
kick in.

Phil Weldon

"Paul" wrote in message ...
First of One wrote:
As you know, some power supplies made by Seasonic and PCP&C are really
single-rail, but were advertised as multi-rail at one time because it
was fashionable. Now single-rail supplies are trendy, you see all kinds
of monster PSUs re-labeled with 50A or even 70A ratings on the 12V.


I just wish the industry had some standards for this. It shouldn't boil
down to some review site opening the thing with a screwdriver, to figure
out how it works, and how it can be used.

Paul



I've heard of the 240VA limit from IEC60950, but it appears to be
optional to support it.

http://www.pcpower.com/technology/myths/

"PC Power and Cooling is once again leading the industry. All of
our power supplies now feature a large, single 12-volt rail. The
design is favored by major processor and graphics companies,
complies with EPS12V specs (the 240VA limit is not a requirement)
and is approved by all major safety agencies such as UL and TUV.3"

I'm not going to argue the merits of that statement, because I don't have
a copy of the appropriate spec that calls up the 240VA limit. I understand
it is traceable to something like 60950, but don't have a copy.

I was referring more to the architecture of the supplies. While
formfactors
has a design document for dual rail supplies, I'm not aware of any
standard
for tri or quad rail supplies. (Maybe design guidance comes from some
server spec ?) And the assignment of connectors, seems to be largely left
to chance. On the plus side, I am finding more documentation than I used
to. A few years ago, it used to be really frustrating to find out
what the wiring plan was. (Took a review article, to get the story. The
manufacturer couldn't be bothered to list it.)

Paul


 




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