As my deviantart and YouTube traffic explode with new Iray users, I'm still seeing a lot of confusion about this. Before we go on, please have a look at my time benchmarks for the scene I made for that purpose, try rendering it at 400x520 on your system, and compare.
We've also got a thread about it on the DAZ forum, where you can see a lot of people's hardware and how they did.
Hopefully this will help remove some confusion:
1. In general, the main thing that affects how fast you can render with Iray is how many CUDA cores and how much VRAM your Nvidia graphics cards have.
If you bought a card one or more years ago and it was a midra