How many WATTs power supply do i need?

[Beowulf]

Building a new system wondering how big a power supply I need? Yes i have
seen sites helping to figure it out but I think it gets more complicated
with a dual core cpu and perhaps (at some point in time) two graphics
cards using SLI.

AMD Athlon 64 dual core X2 cpu, perhaps the 4000 series
1 nVidia GeForce 7800 PCI express 256MB video card
At some point, a second video card (same as above)
4 GB RAM (DDR 400)
3 IDE hard drives
1 DVD-RW/CD-RW drive
1 TV Tuner PCI card
1 wifi PCI card
onboard audio and LAN

 

[Name]

Building a new system wondering how big a power supply I need? Yes i have
seen sites helping to figure it out but I think it gets more complicated
with a dual core cpu and perhaps (at some point in time) two graphics
cards using SLI.

AMD Athlon 64 dual core X2 cpu, perhaps the 4000 series
1 nVidia GeForce 7800 PCI express 256MB video card
At some point, a second video card (same as above)
4 GB RAM (DDR 400)
3 IDE hard drives
1 DVD-RW/CD-RW drive
1 TV Tuner PCI card
1 wifi PCI card
onboard audio and LAN

just go for the largest currently available which I think is 600W.....they
are not expensive now.

 

[Beowulf]

just go for the largest currently available which I think is 600W.....they
are not expensive now.

But is that much wattage really needed? Would 350W suffice? I mean PS used
to be 150 watts, what is around the corner?, 1000W, which is basically a
hot air hair dryer blowing constantly.

 

[Mike T.]

Building a new system wondering how big a power supply I need? Yes i have

seen sites helping to figure it out but I think it gets more complicated
with a dual core cpu and perhaps (at some point in time) two graphics
cards using SLI.

AMD Athlon 64 dual core X2 cpu, perhaps the 4000 series
1 nVidia GeForce 7800 PCI express 256MB video card
At some point, a second video card (same as above)
4 GB RAM (DDR 400)
3 IDE hard drives
1 DVD-RW/CD-RW drive
1 TV Tuner PCI card
1 wifi PCI card
onboard audio and LAN

You are asking the wrong question. It's not a matter of how many watts,
it's a matter of how much current can a power supply sustain on each voltage
rail, and does it have the proper connectors for your components? If you
buy a cheap 600W power supply, it might not be able to handle your planned
rig. But I'm running a similar rig (almost identical) off a 380W Seasonic
(SS series) power supply with no problems at all. I have no intention of
trying SLI. Still, I would think that 450W would be sufficient, if the
power supply is a good brand.

The other thing you need to consider is that PCI Express video cards (some,
anyway, probably including the Geforce 7800) require a power cable with a
6-pin connector from the power supply. So to run 2 of them, you would need
a power supply with 2 PCI Express connections, obviously. -Dave

 

[Name]

On Fri, 17 Mar 2006 15:47:43 +0000, Name inscribed to the world:
..

But is that much wattage really needed? Would 350W suffice? I mean PS used
to be 150 watts, what is around the corner?, 1000W, which is basically a
hot air hair dryer blowing constantly.

many of the new designs employ fan speed controllers so the fan does not
blow at max all the time.

My Enermax runs around 2000 rpm most of the time when its top speed is about
3500 rpm

 

[Beowulf]

.

The other thing you need to consider is that PCI Express video cards (some,
anyway, probably including the Geforce 7800) require a power cable with a
6-pin connector from the power supply. So to run 2 of them, you would need
a power supply with 2 PCI Express connections, obviously. -Dave

I have never heard of PCI-e power cable connectors-- is this something
special on special power supply units, or are there adapaters to use on
the normal power plugs from the power supply (that normally supply IDE
hard drives, etc) that would covert a normal plug to one that fits a PCI-e
video card?

 

[Mike T.]

I have never heard of PCI-e power cable connectors-- is this something
special on special power supply units, or are there adapaters to use on
the normal power plugs from the power supply (that normally supply IDE
hard drives, etc) that would covert a normal plug to one that fits a PCI-e
video card?

There is an adapter that you can buy from newegg, etc., that will take two
hard drive molex type plugs and allow you to run a PCI-Express video card
off of them. However, the expected current draw is so high that it takes
two of your hard drive connectors.

Many newer power supplies include the PCI-Express connector. I just sold
one to a friend of mine (used, long story) that was a OCZ Modstream with a
PCI-Express connector. He needed it, as his PCI-Express computer quite
oddly didn't have a PCI-Express power supply (it came from HP that way!).
And, the power supply was too weak to use the adapter thingie, so the power
supply had to be replaced anyway. -Dave

 

[Paul]

I have never heard of PCI-e power cable connectors-- is this something
special on special power supply units, or are there adapaters to use on
the normal power plugs from the power supply (that normally supply IDE
hard drives, etc) that would covert a normal plug to one that fits a PCI-e
video card?

Nvidia's build advice is here:

http://www.slizone.com/object/slizone_howtobuild_2.html

Scroll through this list, to see "certified" power supplies.
That will make the list of potential candidates a bit shorter.
A lesser supply would be fine, if you aren't going SLI.

http://www.slizone.com/object/slizone2_build.html

Paul

 

[Bob Knowlden]

I recommend a 7900 series card over the 7800. A 7900GT is more powerful than
a 256 MB 7800GTX, and costs less (as little as $300). The 7900GTX is better
than a 512 MB 7800GTX, and is cheaper ($500) and more readily available.

www.evga.com lists PSU requirements for their products. (They are just one
nVidia-based card maker among many, but the requirements ought to be about
the same for all similar cards.) They suggest a minimum of 550W for an SLI
setup with two 7900GTX cards.

Not all power supplies are equal at a given power rating. The critical spec
is the available current on the +12V rail (or rails). See:

http://www.extremetech.com/article2/0,1697,1932947,00.asp

The lowest power supply that supported a pair of high-end cards was a 510W
unit from PC Power & Cooling. It's expensive:

http://www.newegg.com/Product/Product.asp?Item=N82E16817703001

but it is rated at 34A on the +12V rail.

Make sure that your PSU has a 24 pin ATX 2.0 connector, or a 20+4 pin
(split) one that is compatible with both the ATX 2.0 mainboards and the
older 20 pin ATX boards.

Getting one that is specified by nVidia for SLI is probably a good idea,
although it appears that many of those wouldn't be adequate for two high-end
graphics cards. It would be convenient (but not necessary) to have a supply
with two PCI-Express graphics cards power connectors. (The SLI approved ones
will.)


Address scrambled. Replace nkbob with bobkn.

 

[George S.]

High efficiency = less heat = better quality. Think of the future, go 600W
or above. Take note of your PSU bay size, some of the higher wattage PSUs
are server sized.

 

[Jonny]

Total wattage is not of any real consequence regarding your question in the
subject line when choosing a power supply.

 

[fleet]

Building a new system wondering how big a power supply I need?

Read the below urls for help.
http://www.hardforum.com/showthread.php?t=1000883
http://www.hardforum.com/showthread.php?t=844691

I can make it real easy for you. Just get a Seasonic S12-600.

 

[Phisherman]

Sum the power consumption of all your components. Double it--that's
what you should get. Don't skimp, get a quality brand P/S.

 

[Robbie McFerren]

Sum the power consumption of all your components. Double it--that's
what you should get. Don't skimp, get a quality brand P/S.

I had an experience with a bad power supply (turned out to be a bad
driver, but the power supply was nearly dead anyway) and I bought a
Thermaltake after reading reviews on it's actual tested performance. I
have read reviews on 510 watt power supplies that in fact were 510
watts, but they are 510 AC watts not the DC watts that are true. Your
motherboard will be depending on the 12 volt rail(s) so don't skimp. My
computer is odd, even though it is only a year old the CPU gets it's
power from the 5 V rail.

Old power supply:
450 watt JustPC
New Power supply:
420 watt thermaltake

 

[dannysdailys]

Beowulfwrote

..
just go for the largest currently available which I think i 600W.....the
are not expensive now

But is that much wattage really needed? Would 350W suffice? I mean P
use
to be 150 watts, what is around the corner?, 1000W, which is basicall

hot air hair dryer blowing constantly.[/quote:2daa200e35

No, it won't. Your video cards alone can us up to 245 watts a piece.
You need the biggest one you can get. Your power supply will only us
the power it needs to use. You won't be wasting electricity by havin
it

And you know, quite frankly; if video cards want this kind of power
why don't they just have a power brick like an external hard drive

I run a 500 watter and I really don't like having that much under th
hood. I'd rather have a little jack on the back of the card for
separate power supply. Besides, considering what they get for to
end cards, what could it cost? What's one more plug

Don't take any chances, get the largest

 

[creAtive oBscura]

I'd have to recommend this power supply from newegg.com
http://www.newegg.com/Product/Product.asp?Item=N82E16817103937

I just built a system for a friend with it and it may be a bit of
overkill, but I would rather have too much power than too little. It's
really cheap at almost $70 and it is SLI certified, so it will have the
to 6pin connectors plus all the other parts you have. If you want
more, I have to recommend looking at all of Antec's line of products,
they are the only ones I purchase.

 

[adsci]

u missunderstood him.
he spoke about the power consumption not the fan speeds.

i basically think that this wont be that way (1000W).
if you measure todays systems at plug you will get much lower results as
the wattage written on their psus.

my 350W PSU Athlon XP 2000+ rig consumes ~120W on idle and ~150W on load.

my 500W PSU Athlon 64 4000+ rig i havent tested yet, but im sure its not
500W!

the wattage only describes the power it can deliver constantly when ALL
inside-plugs would be maxed out. additionally there is a peak value too.

normally there is no maxing out, but the system is instable when your
12V/5V/whatever V maximum Ampere output is too low for an half of a second.

i think thats all about. your rig wont consume 1000W. ist all about
different voltages and peak consumptions.

m

 

[James West]

On Fri, 17 Mar 2006 15:47:43 +0000, Name inscribed to the world:
..

But is that much wattage really needed? Would 350W suffice? I mean PS used
to be 150 watts, what is around the corner?, 1000W, which is basically a
hot air hair dryer blowing constantly.

why are you running 4GB of ram ? 640K is enough for anyone ))