07-11-2019 04:02 PM
Just wanted to know if anyone has used 2 NVIDIA titan RTX cards in the P920 and if so which NVLINK was needed, the 3 slot or the 4 slot NVLINK Bridge? Was hoping to order one before the machine arrives. Thanks.
07-12-2019 06:34 AM
As Titan is typically considered a GeForce card, I have to lead off with stating that Titan RTX is not officially supported in P920 in any capacity.
That being said, we do have a couple on hand here in the lab and have been able to successfully get up to two of them installed and running cleanly in P920. However, doing so will require some unique cabling due to the power requirements of these GPUs. There are also a couple of other issues that have to be considered.
1. Power - each card will require more than just a single 12V rail to work correctly in P920. Typically this will involve splitting the 3rd available 12V rail for that platform across both cards (with each card also getting a dedicated rail as well).
2. Themals - Titan RTX cards, at least the FE version and the one's I've seen, use Nvidia's multi-fan cooling desing. This cooling design is actually backwards from Nvidia's traditional workstation GPU (Quadro) design in that it takes fresh air from the rear of the card and dumps it out in the system. This is completely reversed from the way ThinkStation cooling works, which is a front to back airflow. A single card doesn't cause too many issues, but you absolutely cannot "stack" two of these types of GPUs next to each other as the upper card will get starved of airflow. To remedy this isn P920, you would have to split the GPU locations with one being below the CPUs, and the other being above the CPUs.
3. Placement - Because of the thermal concern described above, NVlink with Titan RTX wouldn't be possible as there's no way to bridge the gap across the CPUs. However, I don't think NVlink would work even if they physical bridge wasn't an issue because Nvidia typically doesn't support that feature on GeForce class cards in the workstation space. This is actually something we're in the process of confirming now with Nvidia (using traditional blower/impeller style GeForce cards).
Let me know if you still plan to proceed using dual Titan RTX even with the concerns listed above and I can tryto dig up the power cabling information needed to make it work.