This is a list of card features we are interested in. Only high-level stuff is described here.
Lightspeed Memory Architecture
Looks like NV17/18 has LMA : "NVIDIA introduced similar technology with the release of GeForce 3, called Lightspeed Memory Architecture (LMA). This technology eventually allowed the revamped NV17 core used on GeForce4 MX to outperform the GeForce2 Ultra (NV15)" http://en.wikipedia.org/wiki/HyperZ
All NV20 cards have full LMA.
NV30, NV40, G70 cards feature LMA, although some lower end cards (5200, 6200, others ?) don't feature compression.
Color/Depth/Stencil buffer size/accuracy
It looks like the NV05 is the first nvidia card to support a 24 bit z buffer (and 8 bit stencil) : http://www.nvidia.com/page/tnt2.html
What cards support floating point buffers ?
http://www.gpgpu.org/forums/viewtopic.php?t=2149 "NV44 lacks fp16 blending"