Would two RTX 2070 Supers be worth setting up?

For gaming, I wouldn’t buy a motherboard for this. Most games are built around one graphics card, and support for multiple cards is limited. Even where it works, scaling can be uneven and frame pacing may feel worse rather than smoother.

The fact that the cards are different brands is not the main issue. The bigger question is whether the particular game or software supports using both cards at all.

There are still specialized workloads that can use two GPUs, but that depends on the application, not just having two cards installed. Check the exact software you use and whether it supports multi-GPU rendering or computation before spending anything on a board.

Also check the motherboard’s slot layout and power requirements. Two full-size cards can run hot and leave little room for airflow, and a 700 W supply may be a tight fit depending on the rest of the system and the cards’ power limits.

Short version: keep one card in the system and sell or reuse the other. For ordinary gaming, putting the money toward a newer single GPU is usually the cleaner upgrade. You avoid extra heat, power draw, and compatibility headaches without needing a new motherboard.

It’s not completely impossible to benefit from two cards. A few older games and some particular applications can use them, and results can vary a lot by title and configuration. If you already had a compatible setup, testing those specific programs could make sense.

But that’s a pretty narrow reason to buy a motherboard. I’d look up support for the exact games or tools you care about first, rather than expecting a general performance boost.