Then my point still stands, heh. A 4670 will stand up to a 9600GT, therefore, a 5670 which is undoubtedly more powerful than the 4670, by extension, must be the most powerful card that doesn't require a direct PSU power connection.
With the budgt range of performance having exploded in the past couple years, the difference in performance between a 9600gt and a 9800gt keeps gettings smaller and smaller, when compared to what you can get these days.