So im looking to upgrade my 8800gts 640mb. ive decided to try the GTX 460. so i was thinking of getting the 768mb version since i can find them for about $50 cheaper which would be nice on the budget for now. would the 768mb be able to run FPS games with graphics turned up max on 1680x1050 pretty much as good as the 1gb version? im guessing either would be a massive improvement from a 8800 anyways. i was also thinking of doing sli down the road, would that put it on par if not better than the single 1gb?
Yes, for now the added performance would probably not be worth the added $50+.
However, in an SLI system you want all the ram you can get. I learned this the hard way back with my dual 6800GT 256MB cards. They did great in SLI, until a year or so later when games started wanting more than 256MB of ram and performance tanked. So they ran out of ram long berfore they ran out of processing power. Thus, if you can afford it (and plan on keeping these cards for a little while) I'd recommend the 1GBs. As who knows, many games are already needing 768+MB of VRAM and you might get a higher res monitor down the road, or really like high AA, etc.
The difference between the 1GB and 768MB model is more than amount of memory. The 1GB has 32 ROPS compared to the 768MB at 24. It also has a 256bit memory bus compared to the 768MB at 128bit. You can look at this review and decide for your self at the performance difference. http://www.anandtech.com/show/3809/nvidias-geforce-gtx-...
The higher the resolution the bigger gap between the two models will be. At 16x10 there won't be a huge difference in performance, but it is up to you whether the cost difference is worth it. I see some models there is a $50 difference on Newegg, but for example the Gigabyte, it's only $30. I'd spring for the 1GB model if I could unless you are budget limited. Regardless, it will be a nice jump from your old GTS. You also get DX11 support, which is nice in 2010 and into 2011 for new games. I think DX11 is catching on more than DX10 ever did.
Just my own thoughts, I never buy a card with the intent to SLI or Crossfire. I went down that path once and had issue with heat (dual 4870). When you choose a case, motherboard, and power supply, that is when you should decide whether you want to go down the dual card road. I planned it with my mobo and PSU, but my case couldn't deal with the extra heat and overheated my top card. I always suggest a single card setup unless you are ready to deal with the extra heat from dual cards. If you want more performance, sell your card on ebay or craigslist and upgrade. There is always someone willing to buy your card for the right price.