If by RX you are referring to nVidia RTX series, this doesn't work at present for rendering in poser. If you are referring to the AMD RX cards, these also don't work for rendering with poser. GTX 1080and above seem to be running out of stock, but you should be able to get 1060 or 1070cards reasonably priced. I'd agree with ironsoul, that for general responsiveness, single core clock speed of the processor seems to be the limiting factor. FY! rendering with superfly with identical render settings other than bucket size I have found my gtx1080 card about 20% faster than my 14 core 28 thread 3.1GHz i97940x processor. However it might be possible to get equivalent quality in less time using branched path tracing with the cpu, with you can't use with the gpu