Hello Robin88Hood;

A few years ago is pretty vague. How old is the PSU?

You should be OK.
You'll be using the PSU's 2x 6pin PCI-e power connectors in the card designed for 1x 6pin connector and 1x 8pin connector but you should be OK doing that.
 

Robin88Hood

Distinguished
Nov 11, 2011
3
0
18,510
Thanks for reply.
My PSU is 4.5 years old. Too old.

I think i will buy new PSU; 900 W.
http://www.scan.co.uk/products/900w-psu-antec-high-current-gamer-hgc-900-88-eff-80-plus-bronze-sli-crossfire-eps-12v-quiet-fan-atx-
 
If you want to spend a bit less the 750W model has enough power for a CFX setup with 2x HD 6970s and the rest of your system parts.
It has 4x 6+2pin PCI-e power connectors and a hefty 62Amps +12V power rating.
The HCG 900's +12V rating is 70Amps