You would think so, but putting that much hardware on one card forced Nvidia to drastically lower the core clock of the gtx 590. A standard gtx 580 is clocked at 772mhz (core), but the gtx 590 is clocked at 608mhz (core), as well as a lower memory clock (gtx 580 = 4008mhz, gtx 590 = 3416mhz) As a result of this the gtx 580 sli configuration offers on average a 15-35% performance improvement (depending on the game) vs. the gtx 590.

http://www.xbitlabs.com/picture/?src=/images/video/geforce-gtx-580-sli/580sli_specs.png

The cards I bought are also factory overclocked (by the card maker) at 860mhz (core) which should provide an extra bump in performance increase as well. They have a better cooling solution as well vs. the stock one.

http://www.xbitlabs.com/articles/graphics/display/geforce-gtx-580-sli_11.html

gtx 590 cards are also rarer and have a higher cost. The two gtx 580's I bought cost me less than 1 gtx 590. Up until the 680 released the opposite was true (2x580 cost more than 1x590), but now it's reversed. It was a great deal I got on the two cards (and they are already sold out of them.)

With the rumours of the GTX670 being close to the performance of the 580 (probably higher in games but lacking in compute like the 680) and use a lot less power and also be cheaper ($399 has been hovering arround for the 670 http://videocardz.com/32476/geforce-gtx-660-ti-and-gtx-670-specification-leaked) it should push prices down further. It will likely be a better buy than a 580, I mean a quick check on newegg shows that 580s still go for $400+ so 670 could be a much better buy. 

Worth waiting for a couple weeks or so anyway

I recommend an ATI Radeon X1950 :)

In his case it's probably worth waiting to see how they stack up against the gtx 580, performance and price wise. The gtx 580 is a solid choice though as it was the performance king last gen. and it still holds up pretty well against the 680. As long as you can get it for a good price.

As for me, I think I just got a really great deal on my cards. (Taking into account the weak US$) I paid about $370 for each card(tax included). These cards just debuted in January for about $620 each. They aren't vanilla 580 cards; they have a custom designed pcb, nice custom cooling solution, as well as a pretty nice factory OC. For vanilla cards I might have held out, but these are nice. I'm also selling my old cards which takes care of the cost of one 580, so not bad. 

I've seen that the standard price of the 680 in the US is $499 (not including tax) which is nice, but the prices in Japan for it that I've seen range in the $700-$800 area (tax included). I'm guessing that the 670 would take up the old gtx 580 pricepoint(~$600) as the 680 has taken up a higher pricepoint. 

yea that is a good price for 580s you got, still out of my price range tho lol

hmm sooner than expected
http://wccftech.com/msi-geforce-gtx-670-oc-edition-pictured-detailed/

I've been checking and wow, I did get a nice deal on these cards. The next lowest price I've seen for vanilla 580's is 5,000 yen (~$60) higher than what I paid!

Sorry for hijacking the thread, but I just got my 2 cards in the mail today. They are the only gtx 580 cards that support single card multi display so they come with a lot of adapters and cables! mini-hdmi to hdmi, hdmi to dvi, displayport to dvi (only passive though). I'm just using the displayport cable that came with my Dell U2711 monitor though.

http://i21.photobucket.com/albums/b258/smbu2000/P1000295_a.jpg

The cards are extra long with the custom cooler extending past the pcb itself. It still managed to fit alright in my case though.

http://i21.photobucket.com/albums/b258/smbu2000/P1000303_a.jpg

@smbu2000 Damn that looks nice
I'm so jealous right now

Another question.

How do you know if your CPU is bottlenecking your GPU?

I know my CPU won't do this if I do buy a GTX 580, I'm just curious.

Thanks!

Well today I went to the retail store (bought the 580's from the online store) to sell my old cards and saw that they had almost the same deal for the Galaxy gt 580s that I bought! I was tempted to get another one, but the backplate makes things a tight fit in the adjoining slot and I don't think my powersupply would be up to it (Silverstone Strider Gold 850W (peak 950W)).

The two cards are running great though. I tested skyrim at 2560 x 1440 (resolution of my dell u2711) with everything maxed/FXAA on and it runs super smooth at over 60fps (I forgot to turn off vsync). Witcher 2 EE at 2560 x 1440 on Ultra with Ubersampling disabled runs at over 70fps. (With ubersampling on it still runs at over 30fps)

In case you were wondering about my other specs, I have:

Case: Lian Li X900; CPU: Intel i7 2600K Sandy Bridge 3.4ghz@4.6ghz (highest I've run it is just over 5ghz); Cooler: Corsair H60; MB: Asus Maximus IV Extreme (P67); RAM: 2x4GB (G.Skill Ripjaws X 1600), 2x4GB (Corsair Vengeance 1866); Boot Drive: 120GB Intel 510 SSD.

Ooh and I just noticed that Ivy Bridge cpu's are also compatible with slot 1155 mobos (P67/Z68), nice! Although, I have no intention of upgrading my cpu at the moment.