I've two annealed fine silver DC cable for sale, made by Paul Hynes Design Ltd. They are brand new. The connectors are XLR to 6 pin MOLEX which you can use to power your DC-ATX PSU. I got these to use with my SR7T but never eneded up using it. These cables are each around USD $380; my asking price is $215 $175 each which includes paypal fees and shipping to CONUS. Local pickup from NYC is welcome.

For a good appraisal of the difference between annealed copper and annealed fine silver DC leads refer to the following links on HiFi Pig reviews for the SR3 (predecessor of the SR4) and the SR5.