Well according to Nvidia, using a 3-way SLI Bridge with a 2-way setup will have double the data transfer speeds between the two GPU's versus the 2-way SLI Bridge. Quoted Directly from Nvidia Customer Care
" Hello Corey,
Thank you for contacting NVIDIA Customer Care.
This is Matiuj and I will be assisting you with your query. I understand from your email that you would like to know if you can use 3-way SLI Bridge with a 2-way setup.
Yes, you can use 3-way SLI Bridge with a 2-way setup, its compatible. You will get double the data transfer speeds between the two GPU's.
Please feel free to contact us, if you have any further questions.
Regards,
Matiuj
NVIDIA Customer Care "