APPROXIMATE PURCHASE DATE: Till I decide what to buy !
USAGE FROM MOST TO LEAST IMPORTANT: Gaming , I want it to be capable to keep up with new games released in the future ( not the very far future )
CURRENT GPU AND POWER SUPPLY: I'm buying a complete new PC
OTHER RELEVANT SYSTEM SPECS: CPU = Core i7 930
MoBo = GA-X58A-UD3R
RAM = 3x2GB (1800/2000MHz)
PSU = Cooler Master 850W
Case = HAF 922
SLI : Maybe
MONITOR RESOLUTION: 1920x1200 , Samsung LED PX2370 23"inch
ADDITIONAL COMMENTS: I can afford 2xGTX 460 1GB SLI , but the idea is I don't want a set of two cards that can play games smoothly in the future but doesn't support the new technologies then (e.g. higher versions of direct x or model shader ) , but with one card , at some stage it would be weak , so I would have to upgrade it to another card , so I'll get performance increase plus support for new technologies then (e.g. higher versions of direct x or model shader )
well, here's my argument. You could get "one card" with the GTX 480 but 2 x GTX 460's will cost less and perform better 100% of the time. Another option is to get a 5970 from ATI but that will only be 10% better than the 2 X GTX 460's whilst costing much more $$$.
All of the cards i posted will only support DX11 or lower, same goes for the upcoming AMD 6xxx-series cards and Nvidia's next offerings, so, no need to get anything else other than 2 X GTX 460 1GB. I personally like the MSI Cyclones
I would get a GTX 470 and OC it. At your resolution it will probably last you until there are better single card options so you probably won't need to SLI. Forget about the GTX 480, if you are willing to OC then the price/performance of the GTX 470 is much better.
FYI the resolution on that monitor is 1920x1080, not 1200.
You cant do what you are sugesting if i understand you correctly because the newer card with the support for the newer tech wont play nice with the older card in traditional Crossfire or SLI. I beleive there is a way around this using the Hydra chip from Lucid but i cant be 100 % sure if it will work or not. This chip is available on the motherboard or on the cards themselves soon i beleive.
Here is some info that claims it will work with differant generations but im unsure if that means you will get the higher DX version for example or if it would default to the lowest common denominator like dual cards do know with clock speed at the moment. http://semiaccurate.com/2010/08/30/lucid-hydra-gets-off...
Personally i think your best bet is to stick a pair of 460's in now or just go with a single 5870 for now and upgrade to better hardware later if you dont really fancy SLI that much.
I don't know that we'll be seeing a new DX version for a while, and even then, 11 was a huge step up but if they release 12 it probably will only have slight improvements like 10 over 9. A pair of 460s now will be good for several years, and probably by the time you're looking for new ones a new DX will finally be in the works. Not to mention new ATI and NV cards.
Alternatively, give it a few months and see what the ATI 6xxx has to offer.