EDIT: <solution>The T-panel in the UV/Image Editor window takes up a lot of resources and can freeze the GPU. Close the T-panel when rendering.</solution>
I have a less than state of the art GPU (Asus NVIDIA GeForce GTX 560 Ti) (I think it has 1GB of memory)
When I render my fairly complex scene in HD (1920x1080) using 256x256 tile size I get approximately 20 samples per second when I render.
If I increase the size to 170% I still get almost 20 samples per second when I render. But when I increase to 175% I only get about 1 sample per second. My goal was 200%.
My guess is that the memory in the GPU runs out. But I thought that that would simply cause a crash with a memory error message. Is there a way to monitor GPU memory? Or see how much memory is required for a scene in Blender when rendering?
Also, if there are any up to date guides for buying a new GPU for Blender rendering, please give me a link to those.
For instance, is the Titan Z a good choice, or is it just madness to pay that much for a GPU?
Best regards, Erik