You could share your computer set-up, maybe in your profile signature like other members do?
You could enlighten readers about the file size and complexity of your model a little bit?
If the clay model renders ok, but the real render doesn't, I would say it's a material issue.
Maybe you have used procedural grass in your scene.
Maybe there are too big images and/or other complexity with material bake-ups.
Maybe your render settings/preset is abnormally high for your model complexity and/or computer.
I would have suggested lack of RAM first though..
edit. it's not GPU, cinerender is CPU/RAM bound only.
AC25, Rhino6/7+Grasshopper, TwinMotion • Mac Pro 6,1 E5-1650v2-3,5GHz/128GB/eGPU:6800XT/11.6.5 • HP Z4/Xeon W-2195/256GB/RX6800XT/W10ProWS