4850 1gb vs 4870 512mb

No, the amount memory difference will do not offers more bandwidth, where the GDDR5 excel.

The 1GB will help the 4850 to keep better framerate at higher resolution but the core is still lower clocked than the 4870.

It would depend on what resolution you running, and how high you are running all the eye candy, and AA/AF.
Under most conditions, I would venture to say the 4870 is still a faster card.
Although I have not seen benchmarks from the 4800 series on this, it was proven on the 3800 and 8800 series that anything over 512 meg of memory on a single card was more of a marketing ploy than anything. In fact, in most benchmarks, 2 identical cards except 1 with 1 gig of memory and 1 with 512 meg of memory....the 512 meg version of the card 90% of the time was faster.

Running the 2 cards with 1 gig in Crossfire or SLI did show some improvement, as 2 cards together can run higher res, and higher settings all around and the extra memory did show it helped some, but not a significant amount over 2 -512meg cards.

It would be interesting to see if the new cards do indeed make better use of memory over 512 meg than the last series.

Anyone posting here read the anandtech article about the 4870x2 with 2 GB? They compared it, among other things, to 2 x 4870s (512 MB) in CF, and found that in certain scenarios it was still substantially faster.

Link: http://www.anandtech.com/video/sho [...] i=3354&p=7

Based on that, and on past comparisons of cards with 320, 512, 640, and 1024 MB video RAM, I disagree that extra RAM beyond 512 MB is non-beneficial, specifically with games that have complex textures on high resolutions with AA turned on.

I agree, the 4800's are very efficient with using video RAM.

The reason they have different clock speeds is for stability, it makes perfect sense, you pay more for chips capable of higher speeds.

As the chips come off the production line, the manufacturer will grade them into good chips and average chips (very simplistic example). The good chips go into the 4870s, they're stable at higher clocks, the average chips go into the 4850s, because they're unlikely to remain stable at the higher frequency.

http://www.guru3d.com/article/giga [...] i-review/8

ATI's new chips all seem very small in relation to Nvidia's and many of their older chips (2900 anyone?). I believe that you need a certain size die, perimeter exactly, to use a larger bus width. So if this keeps up, it doesn't look like ATI's cards will be using anything more than a 256-bit bus for awhile (if ever). Besides, there's no way the 256-bit bus at GDDR 5 speeds (which get faster than the 4870 uses) will be a bottleneck.