the 5870 compare to 4890 is botllenecked by its mem bandwidth in comparison... if only it was 512bit or 7-8ghz..
then it would in my opinion might bottleneck a pcie 2.0

but in high res games it practically kills the 4890..
this i guess is where the bandwidth doesnt play much role as to computing power
I think thats partly the case, however from reading ~5 reviews so far, I think that is partly that and partly VRAM bound. looking at the benches, the only cards that are able to outperform it are (single or multi GPU) cards that have 1GB++. If I had the money to buy a 5870, I would wait and get one (or two ) that had 2GB mem as I was assuming that would be the case.

Plus Im not sure how many places have used the 9.10 beta drivers that AMD released, in the few test bits I scanned, they used 9.8 I think.