I would like to know why an external graphics card would be slower in performance than an internal card.
At work we have CUBIX boxes. Basically they allow you to upgrade your video cards without replacing your power supply; they also allow the placement of mutliple graphics cards that physically would not fit in a desktop computer. The CUBIX boxes join to the motherboard through PCI-e x16 extension cards and molex cables. The molex is capped at what I believe is 5.0 Gbps. We have two connections to the host machine and each CUBIX box has two 580 GTX cards....so 4 Cuda devices at render; 2048 cuda cores.
Bart Gawboy came out to our facility last week to teach us more about MR in general. He noted that compared to the Maximus system, our system seemed slower on comparable scenes using Iray. Maximus, using both the Tesla and Quadro has 896 Cuda Cores.
So where is the difference coming from? Here are my options:
1. Hardware limited somehow by the molex connection.
2. 4 Cudas devices (one of which is used for display). Is there a significant performance hit if the GUI display is dragging down the whole render?
3. Nvidia handicapping the drivers. Is the difference because the FP64 is being capped?
4. Is Maximus built on PCIe 2.0 or 3.0? and is the max bandwidth of the PCIe being used by the system?
Answering just one of those questions would be helpful.