presentfactory wrote on 2022-02-10, 10:14:

Hello, I have been starting some reverse engineering on a GPU I have, specifically a Gainward PCI GeForce2 MX 400 with the part number (or whatever this code is for) GK06C006N004. Nothing too special there, but oddly when I was looking into some of the GPU registers I noticed the first PMC register (at address 0 in BAR0) which contains card identification information indicates that the chip being used is in fact NV17, not NV11 like would be expected from a card like this. The PCI ID for what it's worth is still 10de:0110 which indicates it should be a NV11 chip (or at least this indicates the GPU is indeed a GeForce2 card and is not being misidentified). I haven't taken the heatsink off the chip so I don't know what the actual markings on it are, but I am tempted to do that to see if it's actually the GeForce2 chip or not, and what revision it is.

I was trying to think about why this could be, the NV17 chip is apparently an iteration on the NV11 one with an added video decoding engine and a few other minor changes, but nothing major like actually having pixel pipelines (or DX8 support for that matter) like the rest of the stuff in the GeForce4 series (where the NV17 chip was supposed to be used) do. Given that, it would make sense that maybe it was used on an older card, but usually you'd see older chips brought forwards into newer low end cards, not backwards like this. Perhaps this was due to binning or something though, for example if the video engine was faulty they could brand it as a GeForce2 and still sell it at the time, but not sure really.

Either way, has anyone else seen something like this on an older card like this? I've not seen any indication anywhere on wikis or databases that this card should come with anything other than a NV11 chip, or that any cards until later on in history started being sold with potential variations in the actual chip being used, so it is just making me curious if this is a rare thing this one vendor did, or perhaps more common.

They used the NV17 for the Geforce 4 MX 420,440,480 which was based on the Geforce 2 MX cards, NV18 was used on the updated MX AGP 8x line. The main GeForce 4 cards used NV25 and NV28 for later refresh models.

Its possible they used some spare/rejected NV17 GPU cores on the late model MX400 GPUs to fill orders that were still outstanding or they started using early NV17 cores on late model MX400 GPUs before switching to GF4 MX420 production. I have seen this before but with CPUs where AMD will repurpose spare high tier CPUs to fill lower tier orders such as 2600x being rebadged to fill 1600x orders

Could be some misreporting going on here too, its possible that since NV17 is an iteration of NV11b that they share many of the same registers and identification internally.