Play games featuring crossfire assistance.
Play games featuring crossfire assistance.
You require three 290s because most current games enable crossfire, making it manageable.
TES offers dual SLI compatibility, which suggests strong Xfire support but unclear three-way options. Typically, three-way scaling performs poorly overall, with few games supporting it and even fewer handling it effectively. You might see around a 20% boost using the third GPU, but this usually only appears clearly at higher resolutions. I assume you're using 1440p or above; otherwise, your performance will likely be limited.
Bethesda tends to struggle with multi-GPU features, making it unlikely that Fallout 3 or any other TES title will gain much advantage. Since their games are primarily CPU-focused, you probably won’t see significant improvements. The 3 290s option is essentially pointless; just use two 290x units instead.
Some games that claim support often struggle with reliability and speed. For instance, certain Battlefield 4 patches turned Crossfire into an unstable experience, causing frequent crashes when enabled. In Shadow Of Mordor, menus become hard to read and objects at a distance flicker. Rather than purchasing multiple GPUs, consider upgrading to a single high-end GPU for smoother performance and fewer issues.
I switched from dual crossfire to a single nVidia card. Not pushing that nVidia line, but trying to minimize crossfire would be wise. There are more downsides than benefits. One issue is stuttering, extra slots on the motherboard, case clutter, and compatibility concerns. It might have changed for R9 models, but I’m not sure.