Curse

my2cent · Apr 26, 2008, 12:56 PM // 12:56

2x asus EN8800GTS 512 SLI
4gig ram
22 inch monitor
3.0ghz duo core
750i sli mobo ( i think)
antec 900 case ( 4 fan )
1x500gig 7200rpm HDD
will my 550 watt PSU be enuff to power all this?

side note : got this system for AUD 2.5k good deal u think>? also comes with g15 keyboard

Tamuril elansar · Apr 26, 2008, 01:03 PM // 13:03

i'm not sure, but i think you need at least 600+ watt.
how many HDD's you use?

my2cent · Apr 26, 2008, 01:09 PM // 13:09

edited 500 gig HDD

Joshie0808 · Apr 26, 2008, 01:55 PM // 13:55

If your running just 1 video card, 550W should be able to do it..
If your running 2, you should probably get at least a 750W PSU.

Nazar Razak · Apr 26, 2008, 02:02 PM // 14:02

if thats in GBP, 2.5k is a rip-off
Two video cards, i recommend 800W.

my2cent · Apr 26, 2008, 02:36 PM // 14:36

wats gbp?? ( oh nvm brittish pound?) well 2AUD = 1 GBP so 2,5/2 around 1.25k in GPB

well b4 the system was
2x en8800gts 512
3.0ghz
2gig ram
sum ramdom case
500gig HDD

in this settin they said a 550 was enuff, but as u can c i also added more ram and changed the case was just wondering will it still run in 550w

Snograt · Apr 26, 2008, 03:08 PM // 15:08

I'd say that 500W is really pushing it in an SLI system - as others have said, 750W would be better. I think GTSs are not too bad on the power eating front, but the graphics cards in some SLI systems can easily eat 400-450W all by themselves.

AUS$2500 is equivalent to £1175 at the moment, so that's not too bad a price - depending on exactly which processor you got, which monitor, what RAm - lots of variables.

Australia is probably much the same as the UK. We get thoroughly ripped off with prices for technology in comparison with USA and even mainland Europe.

Why_Me · Apr 26, 2008, 03:32 PM // 15:32

Watts means nothing. What power supply are you talking about? How many rails? Amps per rails?

Snograt · Apr 26, 2008, 04:36 PM // 16:36

Quote:

Originally Posted by Why_Me

Watts means nothing

Well, considering V=W/A, that's not strictly true, is it?

Sure, you need the 12V rails, but if the graphics cards are drawing 200W each (for example), then you're going to need a PSU with way more than 400W, right?

Brianna · Apr 26, 2008, 04:46 PM // 16:46

Watts do matter, but that isn't all that counts.

For SLI you probably at least want 4 12volt rails that put out at least 18 amps per rail. You'll also notice that most good 1000w + power supplies come with 6 12 volt rails.

nebuchanezzar · Apr 26, 2008, 05:12 PM // 17:12

While I don't spec PSU's nearly as much I used to one serious problem is how the manufacturer rates them. Many are rated running at 20C which is almost impossible for real world results. As a PSU gets hotter it runs less efficiently. Top brands like OCZ and PCPower&Cooling rate at 50C. I believe FSP(Fortron and Sparkle) also do. I have been told that Silverstone does also but never looked it up myself.
A 550 watt PSU from any of those would be able to handle SLi rigs but doubtful if most can. That is why the recommendation for them is around the 700-800 watt range for SLi(or Crossfire as it is essentially the same thing).
Your Graphics cards draw far more power than anything else in you system, even your CPU in almost every case. Having 2 substantially ups that draw.
Amperage is the real important statistic as mentioned by Brianna. Since Wattage is a formula of Amperage * Voltage it is simpler to just talk about Wattage. Google the manufacturer and look at their spec sheet noting the Amperage per rail. Most share Amps on the 3.3V and 5V rails but the important one is the 12 volt rail(s) as that is what your motherboard, cpu, and GC's will be drawing from.

*edit*
In regards to Snodgrat's question it has been debated by many as to your actually maximum needs. Yes many GC's will claim to draw up to 200Watts but rarely actually pull that much power. The question they argue is realistic draw vs. potential maximum. The arguement gets muddier as most PSU's run at around 80% efficiency. I myself have always chosen to err on the side of too much power. If nothing else you should look at your PSU in a similar fashion as your monitor. Both should last you for more than one system. With that thought spending the extra money is easily justifiable as you are saving the cost on your next build/rig and the pricetag is less harsh. The cost of high quality PSU's has really gone up in the last few years. I remember buying a Fortron for about 45 bucks that was rated for 520 Watts (at 50C) but put out substantially more when I tested it myself. I still have that running my sons PC. My current PC is an OCZ 600 that cost my almost 2x as much(and I got a deal on it because new it was even more =]).
Never underestimate the importance of a strong reliable PSU. It is the heart of your PC. It is not a secondary item, especially if you are overclocking or gaming as stability under load is of prime importance

Why_Me · Apr 26, 2008, 06:17 PM // 18:17

Quote:

Originally Posted by Brianna

Watts do matter, but that isn't all that counts.

For SLI you probably at least want 4 12volt rails that put out at least 18 amps per rail. You'll also notice that most good 1000w + power supplies come with 6 12 volt rails.

No, ideally you'd want a single, high amp 12v rail. And most good high end kilowatt power supplies are single rail. This is why wattage doesn't matter, the ampage on the rails powering each component does. As soon as you exceed the amperage limit on a single rail, the system won't run properly.

Tiered PSU quality list.

550w would be enough to power the OP's rig, provided the rails are properly allocated and it's a quality psu.

Snograt · Apr 26, 2008, 07:18 PM // 19:18

All very valid points by everyone with which I heartilly agree. We're arguing inconsequentialities here. (I hope I didn't just invent that word...).

My only point was overall wattage. Sure, GPUs only use a fraction of their maximum rating most of the time, and average rating is important. I feel that, however, peak rating is important too - if you have a 500W PSU on that one occasion where every component decides to hit its peak wattage draw at once you'll know all about it

Sure, it will never happen, but it just endorses the idea that you can never have too big a PSU. Certainly though, you need one that is big and good. Certainly not the place to start cutting money when you're system building - in general, as with most things, you get what you pay for.

Quaker · Apr 26, 2008, 10:32 PM // 22:32

It's silly to say "Wattage doesn't matter". Watts are simply a function of voltage times amps, the more amps, the more watts.

However, there is some truth to it as far as the overall rating of the power supply goes. Some companies will run (for example) the 5v rail by itself and claim it can deliver a certain power level - say 200watts for example. They then run the 12v supply by itself and measure it to deliver 300watts. They then do simple math 200+300=500 and call it a 500 watt supply - but sometimes, especially in cheap supplies, the input circuits (the ones that initially convert the AC mains power to DC) can't actually deliver that much power when all rails are running.
So, even if you assess a power supply based upon the amount of "amps" in say, the 12v rails, the question is "can they deliver that many amps (watts) when the other 12v and 5v rails are also running?"

Snograt · Apr 26, 2008, 10:37 PM // 22:37

Ah, now that leads to a question that was bugging me due to my lack of physics knowledge. The example Brianna posted above with 6 12V rails running at 18A, my mind instantly told me that that would require 1300W. But I kept my mouth shut in case I was totally, noobishly wrong

Brianna · Apr 26, 2008, 11:15 PM // 23:15

Well, I just noticed that most high wattage PSU's would have 6 or greater 12 v rails.

However I did notice that some had one rail only, and as Why_Me posted, it has an insanely high amp output on that one single rail (Which I didn't notice), so I guess it makes sense really.

Admael · Apr 26, 2008, 11:27 PM // 23:27

Quote:

Originally Posted by Brianna

Watts do matter, but that isn't all that counts.

For SLI you probably at least want 4 12volt rails that put out at least 18 amps per rail. You'll also notice that most good 1000w + power supplies come with 6 12 volt rails.

Mine is a kilowatt, and it's 70A on a single +12v rail.

GTS 512 don't consume that much power, you don't need a 800, but you definately need more than 550. A 650 will suffice.

(of course I mean a good power supply, why cheap out on one of the most vital and overlooked components?)

70 amps on the +12v rail, baby!

Brianna · Apr 26, 2008, 11:29 PM // 23:29

Quote:

Originally Posted by Admael

Mine is a kilowatt, and it's 70A on a single +12v rail.

GTS 512 don't consume that much power, you don't need a 800, but you definately need more than 550. A 650 will suffice.

(of course I mean a good power supply, why cheap out on one of the most vital and overlooked components?)

70 amps on the +12v rail, baby!

Yeah I think the one I was looking at was a Silverstone, and it had something like 90amps or something really insane on it.

Mr Pink57 · Apr 26, 2008, 11:34 PM // 23:34

Reason being is multi rail systems are have code to stay within which is 20a per rail while a single rail system does not. I will forever recommend PC & Power Cooling PSU's till the day I die. They are all single rail PSU's with the highest standard.

http://www.newegg.com/Product/Produc...82E16817341011
This will power most high end systems just find it in your country.

http://www.newegg.com/Product/Produc...82E16817256017
I personally use this. Does come in a non modular version which is the OP750. There have been many arguments over modular causing power loss over time however it has been disproven in just about every modular review. I use a Antec P180B so space is a bit limited in the lower chamber therefore I prefer modular.

http://www.newegg.com/Product/Produc...82E16817139006
Crosair has come up in the world of PSU's, a lot of great reviews have come around.

I recommend in the 650 to 750 range for a PSU as my old Enermax 500w would not power my current system which is:
e6300
8800GTS 320mb
36gb/150gb Raptor
X-Fi Fatal1ty Pro
2gb Buffalo Firestix Ram
1 CD/DVD
5 fans

pink

Admael · Apr 26, 2008, 11:37 PM // 23:37

That's nothing! The 1.6kW version of mine has 117A on the +12v rail!

But at 1600W it's only 77% efficient... that's too much wasted electricity.
I need 85% or greater!