hi
am enjoying high end games with my gtx 280 but i want to speed up the rendering time in xsi so am thinking of adding a 3700 fx in the same system would it work?
i dont want to sli them am thinking of something like switching them in modes
without switching them physicaly.
As far as I know having an uber fast graphics card will not effect raytrace rendering. I believe when rendering in 3D software its CPU you want over GPU. But as for pushing polygons around in realtime (Modelling for instance) or testing 3D animation the fx card has a huge advantage over the mainstream gaming card.
As for your hidden question about Raid0.. the onboard controller can probably handle 4 in raid0.. but it would be pushing it. While it will certainly work so far as combining the storage the performance boost would run into bandwidth maxs. For a raid like that it is definitely a good idea to get an add on controller, though they are pricey.