Ah, I see some cards which fit that descriptor. Searching Newegg's GPU section still draws a blank if searched for "Optix", but now I know which series cards run Optix (for the benefit of other curious folk, look for RTX2060, RTX2070, RTX2080, RTX3060, RTX3070, RTX3080, RTX3090). These are PCIe 3.0 or PCIe 4.0, so they will be only for my planned new PC build, as budget allows.

In the meantime, I'd like to retro-fit my old PCIe 2.0 / Win7 workstation to be at least moderately GPU render capable. On Newegg, going to the GPUs, I filtered PCIe 2.0, and then filtered to get only cards with at least 4GB onboard RAM. I see several 4GB GT730 cards, an 8GB GTX1070, and a 6GB nVidia Tesla M2070.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5