Re: GTX570 or Ati 6950 ?
Title of thread I linked to: AMD's Radeon HD 6970 & Radeon HD 6950: Paving The Future For AMD. Pretty apparent they are also talking about the 6950 but I can understand your confusion. Well if you want to start about "features" here we go.
Physx - Really does not add anything to the games I've played. I could really care less if that piece of cloth of there rips in multiple ways instead of just falling down.
CUDA - Were talking games here not development.
3D Vision - Nice to have if you want to spend that much money but again useless to me.
STREAM - No idea what it is and don't care. Sounds about as useless as Physx.
OpenCL - Same opinion was Physx.
Eyefinity - Once again nice if you want to spend that much money.
Those "features" you're on about really mean nothing to the average game. How many people honestly sit there to watch how that piece of cloth rips/falls? Biggest thing for me was price and performance and the 6950 won here.