Is it using my card?

When I render, my CPUs are maxed out for most of the render time, 70 percent the rest of the time.

How can I set it/ensure that Blender uses ONLY my NVidia Quadro FX 4500 X2?

Blender uses the cpu for rendering, not your gpu.

Richard

yup. blender is supposed to do that.
if you want gpu rendering, i guess you could try nvidia gelato…
it’s a renderman-compliant, gpu-accelerated renderer.
never used it, not recommending it, i just know it’s out there.

Are you saying your OS uses 70% cpu on idle?