Gtx 580 stock

Is a 700 watt power supply strong enough to run a gtx 580 ?
i have an ocz modxstream 700 watt power supply

PcGAmeR22 wrote:
Is a 700 watt power supply strong enough to run a gtx 580 ?
i have an ocz modxstream 700 watt power supply



http://www.xbitlabs.com/articles/gra...0_5.html#sect0

GTX 580 264.1 watts

12V slot power = 3 amps
12V 2x3 plug = 6.2 amps
12V 2x4 plug = 12.7 amps

Slot power may come from a different current-limited 12V rail
than the other two.

You need to work out the power drain of your other computer components,
to know whether the 700W is enough. My guess is, it's fine. But
if you have something strange we don't know about (like a pump for
water cooling, or a TEC for the CPU), then anything is possible.

Paul

Thu, 05 Jan 2012 16:58:27 -0500, Paul wrote:

PcGAmeR22 wrote:
Is a 700 watt power supply strong enough to run a gtx 580 ?
i have an ocz modxstream 700 watt power supply



http://www.xbitlabs.com/articles/gra...0_5.html#sect0

GTX 580 264.1 watts

12V slot power = 3 amps
12V 2x3 plug = 6.2 amps
12V 2x4 plug = 12.7 amps

Slot power may come from a different current-limited 12V rail
than the other two.

You need to work out the power drain of your other computer components,
to know whether the 700W is enough. My guess is, it's fine. But
if you have something strange we don't know about (like a pump for
water cooling, or a TEC for the CPU), then anything is possible.

Paul

+1

Bill

This is my rig
intel dual core e7500 2.93 ghz
3 gigs of ddr3 ram
1 cooling fan , a cpu fan of course and its heatsink

PcGAmeR22 wrote:
This is my rig
intel dual core e7500 2.93 ghz
3 gigs of ddr3 ram
1 cooling fan , a cpu fan of course and its heatsink



http://www.xbitlabs.com/articles/gra...0_5.html#sect0

GTX 580 264.1 watts

12V slot power = 3 amps
12V 2x3 plug = 6.2 amps
12V 2x4 plug = 12.7 amps

With the Modstream, those loads are likely on the same rail.

E7500 65W (times 1/0.90 for Vcore efficiency) = 72W or 12V @ 6A
Cooling fans 12V @ 0.5A allocated or 6W

Hard drive 12W (12V @ 0.6A, 5V @ 1A) --- some drives now are much less
Optical drive 25W (12V @ 1.5A, 5V @ 1.5A) --- measured 12V @ 1A on a drive here
with media in the tray

Motherboard plus RAM allocation 50W (could come from 3.3V and/or 5V rails)
USB power from +5VSB, allocate 10W more

Total = 264.1+72+6+12+25+50+19= 448.1W (worst case, actual *will* be less)
On a good day, unlikely to pass ~400W. Total power looks OK.

*******

Now, to check current flow.

Total 12V rail current must be allocated to the various rails
on the supply. If the supply had one big 12V rail, you'd total
all the currents

(3+6.2+12.7)+6+0.5+0.6+1.5= 30.5 amps

If the supply has 12V1 and 12V2, the CPU is on 12V2, the rest on
12V1.

12V1 = (3+6.2+12.7)+ 0.5+0.6+1.5= 24.5 amps
12V2 = 6 = 6.0 amps

This is a picture of the label on the power supply. 25A limit on 12V1.

http://images17.newegg.com/is/image/newegg/17-341-018-Z05?$S640W$

That means the 12V1 is getting close to the current limiter value
of 25 amps. With no CD in the optical drive tray, the optical drive draws
no 12V current (as that is a motor current). So without CD it
is 23 amps. And that's only if the video card can be driven to
the same state as in Xbitlabs review.

So that's the only concern. The overall power rating is sufficient,
but the asymmetric load on 12V is a bit of a concern. If the
current limiter triggers on 12V1, the power supply will shut
off and you'll have your answer (need new supply). If it
stays running, the ~400W actual load should not be a problem
thermally. Sometimes the supply shuts down, because a
common heatsink in the supply is getting too hot.

Paul

thank you for the information
what can i do other than buying a new psu to run that card

PcGAmeR22 wrote:
thank you for the information
what can i do other than buying a new psu to run that card

That's a good question. On the surface of it, not much.
You're stuck with the limitation.

*******

Your first hint the supply isn't enough, is when there aren't
enough PCI Express connectors on the power supply, to properly
power the video card. That's your first hint the supply isn't
right for the job. If the supply has one PCIe connector and you need
two, chances are the output isn't big enough.

Some supplies have a "massive single output". This does two
things for you. On the positive side, you get to use all the
current rating of the supply. For example, if the supply could
make 12V @ 50A and your load is 30A, then there is no problem.

+-----+
| | +---- 12V1
| 12V | |
| @ |----- 50A limit -----+
| 50A | |
| | +---- 12V2
+-----+

There is at least one industry standard, that stated that no more
than X watts should be allowed on a single output of the supply.
The claim is, that is a safety/fire thing. If that 50A output
is shorted or partially shorted, things could get rather warm.

To stop that, some supplies place a current monitor on each
output section. In your case, two shunts are placed in the
structure for monitoring. If either shunt detects more than
25 amps, the supply can shut off. The trip point may not be
that precise - the thing is, to meet the rating, they don't
want it to shut off at exactly 25 amps. It might trip at around
30% more than that. 25 * 1.3 = 32 amps for example.

+-----+
| | +-- 25A limit -- 12V1 This could
| 12V | | (monitor be your
| @ |----- 50A limit -----+ OCP) design...
| 50A | (indirect |
| | thermal +-- 25A limit -- 12V2
+-----+ limit) (monitor
OCP

Another way to achieve the requirement of the standard, is to
use separate transformer and diode rectifier structures for
12V1 and 12V2. But that is a less common solution. In that
case, the rating on the supply label is "real" rather than
contrived. I couldn't find a review of your exact supply
model, so I don't know whether for sure it uses a single 50A
circuit with limiters, or uses two 25A separate outputs. The
separate output idea has mostly gone out of style. When they
do this, the chassis of the power supply is a bit longer.

+-----+
| |
| 12V |
| @ |----- 25A limit ----- 12V1
| 25A |
| |
+-----+
+-----+
| |
| 12V |
| @ |----- 25A limit ----- 12V2
| 25A |
| |
+-----+

So for some reason, a number of brands of supply where the
single massive output is not current limited per output,
they give you all the power you paid for. If current
limiters are present, it's harder to draw that limit.
For example, 25A for the processor side (12V2) is a very
generous rating, when processors don't draw that much.
It would take a server motherboard, with two sockets
and two older generation Prescott-like processors, to
draw that much current. If they'd made the limit a bit
more asymmetric to begin with (like 30A, 20A) that might have
made a bit more sense.

And in any case, even when a supply has the label rating to
meet the job, there is no guarantee it actually works as stated.
With some of the cheaper brands, they take a 350W supply and
put a 500W label on it. And you figure that out, when the
supply "flakes out" on you and either the game exists abnormally
(crashes) or the supply switches off on overheat.

I'd say, give it a try. In terms of power rating, the supply
seems to have a good power rating for the job. Two things
could happen here. The supply might not really be rated for
50A, and the 12V output could be "soft". In which case, you
might hear the hard drive spin up, spin down, over and over
again. That's a hint the voltage is weak. (You can check that
with a multimeter for example.) But if the current limiter of
25A on 12V1 is triggered by your 23A+ load, then you'll have
your answer instantly.

It's possible to mod the power supply, but I'm not even
going to tell you how, for safety reasons. To make the
mod, you have to be *absolutely* sure of the internal
architecture (whether single transformer or multiple
transformer type). It's better to just buy another one,
than to explain to your fire insurance, what the hell you
were doing :-)

Paul

Thanks, Paul. Love the thoroughness and clarity of your response. Now if
we could only get the tech support folks to provide that service. I'll bet
you Don't work tech support...... ;)

T2

"Paul" wrote in message
...
PcGAmeR22 wrote:
thank you for the information what can i do other than buying a new psu
to run that card

That's a good question. On the surface of it, not much.
You're stuck with the limitation.

*******

Your first hint the supply isn't enough, is when there aren't
enough PCI Express connectors on the power supply, to properly
power the video card. That's your first hint the supply isn't
right for the job. If the supply has one PCIe connector and you need
two, chances are the output isn't big enough.

Some supplies have a "massive single output". This does two
things for you. On the positive side, you get to use all the
current rating of the supply. For example, if the supply could
make 12V @ 50A and your load is 30A, then there is no problem.

+-----+
| | +---- 12V1
| 12V | |
| @ |----- 50A limit -----+
| 50A | |
| | +---- 12V2
+-----+

There is at least one industry standard, that stated that no more
than X watts should be allowed on a single output of the supply.
The claim is, that is a safety/fire thing. If that 50A output
is shorted or partially shorted, things could get rather warm.

To stop that, some supplies place a current monitor on each
output section. In your case, two shunts are placed in the
structure for monitoring. If either shunt detects more than
25 amps, the supply can shut off. The trip point may not be
that precise - the thing is, to meet the rating, they don't
want it to shut off at exactly 25 amps. It might trip at around
30% more than that. 25 * 1.3 = 32 amps for example.

+-----+
| | +-- 25A limit -- 12V1 This could
| 12V | | (monitor be your
| @ |----- 50A limit -----+ OCP) design...
| 50A | (indirect |
| | thermal +-- 25A limit -- 12V2
+-----+ limit) (monitor
OCP

Another way to achieve the requirement of the standard, is to
use separate transformer and diode rectifier structures for
12V1 and 12V2. But that is a less common solution. In that
case, the rating on the supply label is "real" rather than
contrived. I couldn't find a review of your exact supply
model, so I don't know whether for sure it uses a single 50A
circuit with limiters, or uses two 25A separate outputs. The
separate output idea has mostly gone out of style. When they
do this, the chassis of the power supply is a bit longer.

+-----+
| |
| 12V |
| @ |----- 25A limit ----- 12V1
| 25A |
| |
+-----+
+-----+
| |
| 12V |
| @ |----- 25A limit ----- 12V2
| 25A |
| |
+-----+

So for some reason, a number of brands of supply where the
single massive output is not current limited per output,
they give you all the power you paid for. If current
limiters are present, it's harder to draw that limit.
For example, 25A for the processor side (12V2) is a very
generous rating, when processors don't draw that much.
It would take a server motherboard, with two sockets
and two older generation Prescott-like processors, to
draw that much current. If they'd made the limit a bit
more asymmetric to begin with (like 30A, 20A) that might have
made a bit more sense.

And in any case, even when a supply has the label rating to
meet the job, there is no guarantee it actually works as stated.
With some of the cheaper brands, they take a 350W supply and
put a 500W label on it. And you figure that out, when the
supply "flakes out" on you and either the game exists abnormally
(crashes) or the supply switches off on overheat.

I'd say, give it a try. In terms of power rating, the supply
seems to have a good power rating for the job. Two things
could happen here. The supply might not really be rated for
50A, and the 12V output could be "soft". In which case, you
might hear the hard drive spin up, spin down, over and over
again. That's a hint the voltage is weak. (You can check that
with a multimeter for example.) But if the current limiter of
25A on 12V1 is triggered by your 23A+ load, then you'll have
your answer instantly.

It's possible to mod the power supply, but I'm not even
going to tell you how, for safety reasons. To make the
mod, you have to be *absolutely* sure of the internal
architecture (whether single transformer or multiple
transformer type). It's better to just buy another one,
than to explain to your fire insurance, what the hell you
were doing :-)

Paul

Tom wrote:
Thanks, Paul. Love the thoroughness and clarity of your response. Now
if we could only get the tech support folks to provide that service.
I'll bet you Don't work tech support...... ;)

T2

I wish the info was on a website somewhere. I've only
been piecing this together from info here and there.

For example, at one time, I used to take the 12V1 and 12V2
thing verbatim, that when you saw that, it was two transformers
and two separate circuits. Until I read somewhere, instead
they were faking it with one transformer and two monitor
circuits.

There are a couple good power supply review sites, like
jonnyguru, that have some of that kind of info. Some sites
disassemble the supply, for a look at the design.

There were only a few, truly independent output supplies. I
remember a picture of one, with four transformers inside it,
and the chassis was a bit longer than your average supply.
While that might meet someone's idea of safety, it isn't
very convenient for users. Supplies like that, you're
highly likely to only use three of the four outputs.
And end up paying for one of them, for nothing. The
other issue with those kinds of supplies, is getting
reliable info on which wires are connected to 12V3 and 12V4.
Again, a supply review might be the only source of info
(where the reviewer requested the info directly from the company).

Paul

does the 580 require 2 pci wires
i have 2 they came with my mod power supply