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Power supply requirement for 2 Nvidia GTX in SLI?

 
 
huLLy
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      03-12-2008, 10:13 AM
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


 
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Phil Weldon
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      03-12-2008, 03:52 PM
'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...rm_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" <(E-Mail Removed)> 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>
 
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Paul
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      03-12-2008, 10:41 PM
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
 
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Mr.E Solved!
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Posts: n/a
 
      03-12-2008, 10:51 PM
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.
 
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Paul
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      03-13-2008, 12:07 AM
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
 
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First of One
Guest
Posts: n/a
 
      03-13-2008, 01:45 AM
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" <(E-Mail Removed)> wrote in message news:fr9qsa$scb$(E-Mail Removed)...
> 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



 
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Paul
Guest
Posts: n/a
 
      03-13-2008, 03:36 AM
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
 
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Phil Weldon
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Posts: n/a
 
      03-13-2008, 03:41 AM
'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...rm_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" <(E-Mail Removed)> wrote in message news:fra74b$td1$(E-Mail Removed)...
> 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


 
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Paul
Guest
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      03-13-2008, 04:09 AM
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...rm_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" <(E-Mail Removed)> wrote in message news:fra74b$td1$(E-Mail Removed)...
>> 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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Phil Weldon
Guest
Posts: n/a
 
      03-13-2008, 01:11 PM
'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...rm_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" <(E-Mail Removed)> wrote in message news:fra923$2pd$(E-Mail Removed)...
> 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...rm_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" <(E-Mail Removed)> wrote in message news:fra74b$td1$(E-Mail Removed)...
>>> 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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