My Old video card needed one 6-pin power cable, but the 6870 requires two.
My case only has one 6-pin cable, and NO molex power cables at all. All SATA, so the included power adapters don't help.
What do I do?
For a system using a single Radeon HD 6870 graphics card AMD specifies a minimum of a 500 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 30 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.
Total Power Supply Wattage is NOT a crucial factor in power supply selection!!! Total Continuous Amperage Available on the +12V Rail(s) is the most important.