GTX 580 SLI PS..do i need to upgrade?

[imaheadcase]

I currently have a SeaSonic X750 Gold 750W ATX12V V2.3/EPS 12V V2.91 SLI Ready 80 PLUS GOLD Certified Modular Active PFC Power Supply. I decided to go SLI instead..do i need better than that?

I won't overclock the cards. I will be overclocking the new SB-E cpu when it comes out though, doing a system overhaul.

Been getting some mixed info on how much power i really need. One said i need 1000watt, another said mine was fine.

 

[stahlhart]

http://forums.anandtech.com/showthread.php?t=2196276

 

[imaheadcase]

http://forums.anandtech.com/showthread.php?t=2196276

So? Its just a thread of people bitching about a guys setup. Nothing to do with my question.. any thread with people arguing with that Toyota idiot is something never to link to.

 

[stahlhart]

So?

http://forums.anandtech.com/showpost.php?p=32367723&postcount=14

Whatever.

 

[imaheadcase]

Sigh, could of just linked to the actual article i needed instead of a useless post.

thanks anyways..

Here is what you wanted to post.
http://www.anandtech.com/show/4008/nvidias-geforce-gtx-580/17

 

[jacktesterson]

http://forums.anandtech.com/showthread.php?t=2196276

If we all did this, we'd never have anything to talk about it.

 

[stahlhart]

You're both correct. My bad; sorry.

 

[MarkLuvsCS]

I have the same PSU powering a x6 @ 4ghz 1.45v and GTX 470 SLI @ 775/2000 1.075v. I've seen it peak to ~750w with the later stages of Vantage that stresses both GPUs to the max. typically in gaming though I've only seen it hit between 650-700w. I know the 580s will draw more power but I think the difference is going to be negated by the power used by my CPU vs. yours. Not to mention my cards are both overclocked a fair bit.

 

[TakeNoPrisoners]

To be safe I'd use at least 850w.

 

[boxleitnerb]

I have 2 580s in SLI and a 2600K@4,3 GHz. At most I'm measuring 700W at the wall. So the unit has to provide roughly 640W. Your PSU should be fine, especially since the Seasonics are a bit underrated. Don't fall for the watt hype.

 

[ElFenix]

777 at the wall. anand doesn't specify the PSU unfortunately. if it's a gold model that's about 700 watts output. if it's bronze it could be about 600 watts output.


gold 750 should work. as stated in the other thread (which answered your question) those are seriously overbuilt for the rated wattage (in part because the efficiency of any power supply drops off as it nears its maximum, so to meet the high efficiency it's easier to just label it lower than the maximum).

 

[lehtv]

(in part because the efficiency of any power supply drops off as it nears its maximum, so to meet the high efficiency it's easier to just label it lower than the maximum).

I don't think that's really true. Are there any 80+ silver units that act like 80+ Gold until they start to approach their rated wattage? There's also the additional problem that 80+ rates at 20% load as well, and below this point you see efficiency go down just like you see it decline above 100% load. It'd obviously be easier to achieve the desired 80+ rating at 20% by not underestimating the total capacity.

 

[ElFenix]

sure it is. the dropoff isn't right below 20% for most supplies: the seasonic X400 from a couple years ago is 80% at 42 watts. that's just about 10% of rated. the recent x760 is 86% efficient at 85 watts. that's also about 10% of rated.

so you just move the goalposts a bit to take advantage of the fact that 20% is the lowest rating 80plus tests for. and the two supplies i mentioned are ones where the goalposts had already been moved.


there's overload tests all over the place showing these things are underrated.

 

[TakeNoPrisoners]

I have 2 580s in SLI and a 2600K@4,3 GHz. At most I'm measuring 700W at the wall. So the unit has to provide roughly 640W. Your PSU should be fine, especially since the Seasonics are a bit underrated. Don't fall for the watt hype.

Yea because it is such a horrible thing to be safe.

 

[lehtv]

the seasonic X400 from a couple years ago is 80% at 42 watts. that's just about 10% of rated

According to BFG10K, "Seasonic told SPCR that the components in the X-400 are good enough to be rated at 700W if the unit had a fan". That'd be like 6% of rated wattage for a 700W unit, but 80% efficiency?

there's overload tests all over the place showing these things are underrated.

That doesn't prove the reason they're underrated is to get the efficiency ratings. I'd say it's far more likely is they're underrated because they're designed to be able to run at the rated wattage whenever needed during the whole 5-year warranty period. Running a PSU at such a high load will decrease the maximum capacity over the years, but being underrated, this isn't really an issue. And as I said, where are the 80+ silver rated units that act as if they were 80+ gold until they approached maximum wattage? Because that's what we'd expect to see if the 80+ gold efficiency rating was a matter of underrating the maximum capacity.

 

[ElFenix]

silverstone strider plus 750 does exactly that. acts like a gold supply and then just misses at 750. silverstone st1500 is also at or well within the margin of error of the measuring equipment for gold on 20% and 50% and then falls off for 100%. didn't take much googling to find that.

 

[lehtv]

silverstone strider plus 750 does exactly that. acts like a gold supply and then just misses at 750.

Yet it is underrated by 100W. http://www.hardwaresecrets.com/article/SilverStone-Strider-Plus-750-W-Power-Supply-Review/911/8

 

[BTRY B 529th FA BN]

Get a wattage reader - like 20$ from Home Depot for a rough estimate. But look at the rails on the PSU to see if you have enough to cover requirements. And sometimes games don't use all the GPU power. Games like Crysis will though. Crysis is a good point of reference.

 

[Spikesoldier]

i would go with 1000W quality unit, especially if you have a power hungry cpu.

 

[bunnyfubbles]

FWIW I have the X760 running a 4.7GHz 2600K and stock GTX580s in SLI. 2 x SSDs, 4 x HDDs, 6 fans and the H100's pump as well.

theoretically such a setup should be able to push beyond 750 (or 760) W, but thats only worst case scenarios with artificial benchmarks and stress testing tools

 

[TemjinGold]

Yea because it is such a horrible thing to be safe.

It may be horrible because he already has the x750. It isn't like he's trying to decide between two to buy. So if there's no reason to waste a pile of cash buying something he doesn't need, that is pretty horrible.

Honestly, I would say get it, load it up with whatever you have is the most power hungry, then get a watt meter and measure it. If you are comfortable with what you see, go with it. Seasonic is far from crap, so if it ends up not being enough, you will crash when loading it up, so that will tell you. The Seasonic won't take your parts with it or anything if it turns out to be woefully inadequate (which I doubt it is.)

To play devil's advocate, some of you are saying "get an 850 to be safe." Well if 850 is completely safe, then I seriously doubt you will actually hit 750 in use because all the people arguing for "being safe" would surely have factored in more than 100 watts for margin. Hence, you should be fine. Heck, if some guy ran two 580s on a 650 watter, I don't see why you would have a problem with a Seasonic 750.

 

[BTRY B 529th FA BN]

only logic i see in "playing it safe" is to not run it at 90-100% capacity, e.g. running 739w of a 750w PSU Nothing wrong with it, the idea back then was to not run things at peak wattage of the PSU to keep within efficiency range but nowadays they have the Bronze, Silver, Gold, Platinum ratings that help keep a standard with PSUs