GTX 680 SLI Power Question

purple stain · Jan 28, 2014

I'm looking to upgrade to a second GTX680.I've used the PSU Calculator but I'm not sure about the overclock wattage and if I should be worried about capacitor aging.My main concern and which is what I'm asking you guys is my PSU able to handle this setup.The PSU calculator is saying I would be running at 627watts with the SLI.

2500k @ 4.8ghz @1.44v
MSI Z68A-GD65(G3)
8GB DDR3 1600mhz(2x4GB)
OCZ ZT 750watt

Brantyn Gerik · Jan 28, 2014

I would definately worry about the age of the psu, as well as the quality and sli compatibility of the psu. Yes, the wattage is there, but the 680's require a higher amp rating than a non sli ready-lower quality psu will put out

purple stain · Jan 28, 2014

Brantyn Gerik :

This is my PSU
http://www.newegg.com/Product/Product.aspx?Item=N82E16817341052

It's 2 years old.

dgingeri · Jan 28, 2014

I have a Core i7 3930k and two GTX 680s, and the highest my computer has tapped from the wall has been just under 500W, and that was while pushing high usage benchmarks. That's after the inefficiency of the power supply (Corsair HX750) is figured in. Internal to the system, I'm probably using around 400-450W at most. I don't think your PS will have any problems at all with it. Mine sure doesn't.

Brantyn Gerik · Jan 28, 2014

Your psu won't have any problems, BUT overclocking is not advised, as the amperage output of the psu is slightly low for dual 680's. This is my personal recommendation. The corsair hx series is a much higher quality psu than the one you are using. The worst that will happen is a system shutdown, so it won't hurt to try

dgingeri · Jan 28, 2014

Actually, that OCZ power supply isn't a bad one. It reviews quite well. Several reviews showed good efficiency and very low ripple.

for example: http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story3&reid=262

In addition, with a 2500k running 4.8GHz and only 8GB of memory, I doubt he'll even use as much power as my machine. I have 2 hard drives, 4 SSDs, a 10Gbe NIC, and a Soudblaster Z in my system and it only pulls 449W when running Furmark or 425W when running Futuremark. That OCZ PS should be able to handle 400-420W of usage without any trouble. Nvidia has been blowing their PS recommendations way out of proportion since the old GTX 480, and the GTX 680 recommendations are far worse than any.

purple stain · Jan 29, 2014

So no problems with the GTX680 SLI, OK.Now for my other question.Would it be better to go with the GTX 680 SLI or sell my current GTX 680 and pick up a GTX 780? I was also thinking about waiting for the GTX 800 series since it's only a month out but I'm not sure what the initial launch card will be or how much it will cost.

dgingeri · Jan 29, 2014

The 680 won't pair with a 780, or 770 as the chip is the same between the 680 and the 770. The 780 is a different chip. It will only pair with another 680. Sorry. I dealt with the same question.

Brantyn Gerik · Jan 29, 2014

The 800 series is more than a month out. The only new architecture chip they are releasing next month is the 750ti.
initial launch price for flag ships for nvidia has gone up to roughly $700

Dgingeri needs to read your comment a little better, but he is right lol

the 780 is actually a noticable jump up from the 680, but it's not a HUGE jump. it may let you go from max settings with no aa in crysis 3 to max settings with 4xmsaa

purple stain · Jan 29, 2014

Lol.Got a little crossed there?

Well you make the 800 series sound like just another refresh.But when I read the Wiki article they mention some very interesting things.

http://en.wikipedia.org/wiki/GeForce_800_Series

The Maxwell architecture, the successor to Kepler, will for the first time feature an integrated ARM CPU of its own.

Well what would you guys do? Go for the GTX 680 SLI or a single GTX780?

dgingeri · Jan 29, 2014

your choice: spend near $400 for a second 680 for about an 80% increase in many games but less than 10% in some or spend $520 for a 780 with only a 40% increase in nearly all games. It's really a tough call, especially if you have some games that won't take advantage of SLi at all.

I chose SLi, but it didn't help most of my games hardly at all, but did help one significantly. I kind of regret it sometimes while playing WoW or Diablo3, which didn't hardly see an improvement at all, but then I start up STO and see just how much it helped that.

Brantyn Gerik · Jan 29, 2014

Personal recommendation is usually to sell old card and upgrade to a newer more powerful one, as a single card is more efficient, causes less heat, and is more consistent in performance than dual card solutions.

your power bill, case temps, and frametime variance will all thank you for choosing a single card

purple stain · Feb 6, 2014

Just wanted to give you guys an update.I decided to go with another GTX680.I also bought one of those kill a watt meter just to be sure.And although I don't have the second card yet I ran Prime 95 and Kompbuster to max out everything and I'm only pulling 395 watts.I found it hard to believe it was that low but I don't think I'll have any problem at all running the second card.Thanks for all the help.

Brantyn Gerik · Feb 6, 2014

It's not just about wattage remember, the psu needs to be able to output the right amperage too

purple stain · Feb 7, 2014

Taken from an old post...

For a system using two GeForce GTX 680 graphics cards in 2-way SLI mode NVIDIA specifies a minimum of a 750 Watt or greater power supply that has a combined +12 Volt continuous current rating of 53 Amps or greater and that has at least four 6-pin PCI Express supplementary power connectors.

My psu has 60 amps on a single +12v rail.Is that cutting it to close or do I still have some headroom?

Brantyn Gerik · Feb 7, 2014

no it's cutting it close at each 680 needs 42 amps. don't overclock

dgingeri · Feb 7, 2014

No, each 680 doesn't need 42 amps under any circumstances. Nvidia states 42 amps minimum for the power supply because it needs to power the whole system. When going with a pair of 680s, you just add about 15 amps. Since that is at 12V, 15 amps makes for 180W. (W=V*A) There's some headroom to overclock on that power supply. In addition, that recommendation is only under the most severe circumstances. Most of the time gaming won't even bring you within 80% of that rating. Some benchmarks might, though.

Mine is only rated for 62A on the 12V rail, and I have no problems with overclocking both my GPUs and my CPU. Under normal gaming, with those all mildly overclocked I still have plenty of headroom on my power supply.

Edit: Apparently, my memory isn't the greatest at accuracy. I remembered them saying during the initial reviews that the GTX680 was 180W, but I looked up the specs and they say 195W. So, each GTX680 uses about 16.3 amps, not 15 as I originally stated. Not a huge difference, but accuracy must be maintained. Even if you overclock it to use the maximum 225W the connectors are speced to deliver, that's still only 18.75 amps. So, add up the two 680s overclocked to 225W levels, 37.5 amps, plus your CPU, memory, motherboard, and drives, and you're still probably under 50 amps on that 12V rail.

dgingeri · Feb 13, 2014

How's it going so far? Do you have the second 680? Is it working?

purple stain · Feb 16, 2014

Yeah everything from a power standpoint is fine.But I forgot how terrible multi card setups can be.Stuttering and the lack of supported games makes me feel like I wasted my money.I wondering if it would be better to just use the 2nd GTX 680 as a dedicated PhysX card.

GTX 680 SLI Power Question

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