Are you refering to the PCI 256-P1-N400 vs. the 512-P1-N402?
The datasheet for the PCI (not express) 256 MB N400 indicates a 1064 MHz memory clock, whereas the 512 MB N402 is only at 532 MHz. I wonder if this is correct? I called eVGA on this over a year ago and they confirmed it was something to do with memory technology.
The N400 thus has an 8.5 GB/s memory bandwidth, whereas the N402 has only 4.26 GB/s. Just going off the datasheets, I bought the N400 256 MB about a year ago in favour of the 512 MB version. I'm not sure how much performance this actually translates into the system on a PCI bus though. It would probably help if these cards were run on a 66 MHz PCI system, which is supported (according to eVGA).
I am curious why the AGP version of the 6200 doesn't have any cards with an 8.5 GB/s memory bandwidth? Are the PNY cards any better than the eVGA cards? I can't seem to find the same speed-based datasheets for the PNY cards.
I'm trying to find the best fanless AGP NVIDIA graphics card which is keyed for AGP 2X and 4X, not just 4X/8X. The eVGA 6200's are keyed for AGP 2X and the NVIDIA 6200 datasheet claims it is AGP 2X compatible. Some of those fanned eVGA NVIDIA cards above 6200 are keyed for AGP 4X/8X only.