Just as a follow-up to my last post that I have the power issue resolved, the S3 is now configured and running smoothly, mining on 2 pools. The CX600 seems perfectly capable of handling the S3, at least in this basic configuration.
Like I have already stated, if CX500s are able to handle my overclocked S3s (up to 41.7C or 107F ambient room temperature), the CX600 would be more capable.
I'm glad that you are now hashing. Consider yourself lucky that you didn't fry your S3 or your PSU when you inadvertently connected the PCIe power connectors in the wrong orientation.