Mismatched SLI: GTX 970 and GTX 550 Ti Together

Question

Can I run my current MSI Limited Golden Gaming Edition GTX 970 4GB and a GTX 550 Ti together with an SLI bridge?

The GTX 550 Ti doesn't require another power connector but pulls power off the motherboard.

Answer 1

This is not possible. From the NVIDIA FAQ page on SLI:

Can I mix and match graphics cards that have different GPUs?

No. For example, an XXXGT cannot be paired with a XXXGTX in an SLI configuration.

While the NVIDIA example isn't particularly well explained, they do make it clear that different GPU architectures are unable to be used in SLI.

As others have mentioned in the comments, even if this SLI configuration were possible it would limit the GTX 970 from maximum performance.

There is another option: You could use the GTX 550 Ti as a dedicated PhysX card. While the benefits of this are limited primarily to games using PhysX, it is a potential solution if you really want to have both cards in your system.

Even in this configuration, it is possible for the dedicated PhysX card to bottleneck your system. Again, this depends on the graphics cards being used. It is worth experimenting with, however, as most of the information out there is on forums, with users commenting on whether or not they think performance increases or decreases!

For example, one user on Reddit suggested that when they used a 970 with a 580, they still lost performance. Another user suggested that, in their experience, for a 970 to benefit from a dedicated PhysX card that is a GTX 670 (equivalent or better) should be used.