What PSU do I choose?

Hi.

I am in the near future going to buy either 2x Asus GTX 970 Strix or MSI GTX 970. I have not chosen yet, but that does not matter the case as they both use a single 8pin connector a far as i know. The problem is, that the power supply i got at the moment is not semi modular or modular, just regular and the graphics are only 6 pins. Am I gonna need to grt a new PSU? I'm currently rocking a 750w bronze Coolermaster psu and 2x MSI twinfrozr 3 660 in SLI config. 

660 and 970  power consumption, apear its gonna draw 50w more that what you heave now 

http://www.anandtech.com/show/8568/the-geforce-gtx-970-review-feat-evga/15

http://www.anandtech.com/show/6276/nvidia-geforce-gtx-660-review-gk106-rounds-out-the-kepler-family/16

The PSU might not be enough for the new setup, but hard to comment since you did not exactly specify the current PSU you heave.

check the psu if it has the option to split to 2x8 + 2x6 pin setup and how many rails it has.

 

750w will be more than enough for 2 970's.