Conclusion: The FirePro V3900 is significantly faster than its V3800 predecessor. It costs ~$15 more than the V3800, but delivers an average of 20-25% better performance. Depending on your workload, that boost can be as high as 100%. While Nvidia wasn't able to provide us with a comparison card to test, the company told us that it expected the FirePro V3900's performance to rank somewhere between a Quadro 400 and a Quadro 600.
Pros: Strong performance for its price point, Significant improvement over the V3800
Cons: Advertised support for >2 displays depends on specific, specialized hardware