Questions about Potential 5870 crossfire

I recently have felt the urge to upgrade GPU to something substantially more powerful than the 5870 I am currently using and Although from what I have seen of the GTX 580 it still seems that every year the Top Tier GPU's keep getting higher and higher in price (e.g. performance is not going up in relationship to $/fps at first glance at least). I have Pondered over getting a EVGA GTX 570 Superclocked but i feel it would be more of an lateral move (yes i know the 570 is somewhat better than the 5870) and not really be worth the $370 upgrade, however for $250 i can get another 5870 and xfire them.

Heres my predicament, I cannot seem to find any reference cards with exception to a few diamond cards floating around at some etailers....and from my brief searching, diamond is like playing the warranty lottery if something goes wrong, you don't really know what will happen. So can I....

(A) X-Fire 2 cards as long as they are the same clocks and memory, I do not want micro stuttering, and want to do everything possible to rule out problems before they happen.

(B) do the non reference coolers, the ones with a fan in the center of the card and openings in both ends, dump a significant amount of hot air into the case

(C) Is a Antec signature 850w up to the job of X-firing these cards, it has like 65A on the 12v rails, and has both a pair of 6-pin pcie plugs and 8-pin pcie plugs.

I am trying to get most performance increase for the money, and yes the 580 would be a easier upgrade notwithstanding the price, but if i can equal or better the FPS on the majority of games for $250 and my system is up to it than i would prefer that route. Also my motherboard has 4 pcie x16 slots and they ones i would use for dual xfire have one space between them so my motherboard is def up to it.

I was in the same boat when I had my 5870 and decided to upgrade to the 6970 instead of Crossfiring with a second 5870. I bought a Diamond 6970 for $400 and sold my 5870 for $200 so I upgraded for only $200 and I will use less power than Crossfiring two 5870's. There was about a 15-20% performance gain which is good enough for me and less power draw. Furthermore, I didn't run the risk of having to upgrade to a better psu if it wasn't up to running two cards.

I also thought seriously about getting the GTX570 instead of the Radeon too. I'm hoping that as the drivers mature for the 6900 series, performance will keep increasing as well and make it a decisively better card than the GTX570.

First off the PSU you have will handle it. You can X-fire AND 58xx including 5850's and 5830's, though I wouldn't recommend doing that. All 5870's run at 850mhz stock. The non-reference cards won't micro stutter or be any different than a reference other than their overclocking headroom and coolers they use. 5870's with different clocks shouldn't stutter but that the slower card will bottleneck the other one, so it's best to be at same clocks. The card will dump a good amount of hot air but if you have good case ventilation that shouldn't be too big of a deal. Non-reference cards without voltage control aren't good at overclocking so don't expect much for that.

The best bang for buck scenario for you will probably be getting another 5870, however I would wait if I were you for the 6990 and Nvidia's dual gtx 580 card. This should drive prices lower, offer more choices and competition and if you sell your 5870 and get one of those cards, that might be your best option.

So what you are saying BDA1967 is you would'nt have any issues with Diamond as a brand, and you have experience with them. I think that all cards that have the AMD logo on the PCB are reference, even if it is another board partner who puts their stickers on it. I might just purchase the other 5870 and if available add some type of in house warranty on it so that if the Diamond wants to act up and not play nice with a RMA i can go to the Retailer for service.

Also do you think that the Drivers will really account for a massive increase in performance, e.g. there is that much potential to be unlocked with a better driver set?

I've owned two Diamond brand cards with no issues. Not sure on the drivers though, I'm just hoping that's all.