Those video cards will be a complete waste in bryce. Unless your using max etc you wont even notice and even then they are for the moving huge numbers of triangles PRIOR to hitting the render button. Best thing you can do is buy a 2nd comp with a most basic of video card, small harddrive and even a cheap video switch for display. Let that one do the final renders so your main is still usuable for other projects. Best you can do is the top end cpu and even then youll see only a 3x improvement. Sadly, as ive seen from back on my old p2-400mhz, every time ive upgrade, the scene got more complex until we are back into a 3-4 day range worse case picture. If you got a fantasy pc 100x faster then anything on the market now.... in the end all most would do is turn on volumetric render etc and bang youd still be 3-4 days haha.