Honestly, I think I'd wait to see what the new cards bring to the table. The wait shouldn't be too much longer and it's probably worth at least seeing what kind of performance gains the new memory architecture brings with it.
As seen here, the 290CF calls for a 1000w PSU anyhow. We know it can run ok with an 850w unit, or even a very, very good 750w unit in some cases, but you're going to be severely stressing that PSU in CF at only 750w.
Honestly, I think I'd wait to see what the new cards bring to the table. The wait shouldn't be too much longer and it's probably worth at least seeing what kind of performance gains the new memory architecture brings with it.
As seen here, the 290CF calls for a 1000w PSU anyhow. We know it can run ok with an 850w unit, or even a very, very good 750w unit in some cases, but you're going to be severely stressing that PSU in CF at only 750w.