Your S3 unit exhibiting similar symptoms with two different and very capable PSUs (600W & 1300W) is not likely a PSU issue. It's more like a connectivity/networking issue (red LED on) or perhaps, the unit itself is defective.
With a CX500, each of my S3s which are overclocked to 243.75M (491 GH/s) pulls 413WAC at the wall at 29C ambient room temperature. At 85% efficiency (80 Plus Bronze), the S3 requires 351WDC from the CX500. The CX500 has a maximum of 456WDC (38A) on it's single +12V rail. Therefore, the S3 is only exerting a 77% load on the CX500's +12V rail which is very acceptable and still provides a lot of headroom.
The CX600 (similar efficiency as the CX500) has a maximum of 552WDC (46A) on its single +12V rail. Therefore, the S3 would exert an even lower load on the CX600 at 64%.
I'm not sure what you meant by "crobar it" but if the CX500 is able to run an overclocked S3, it follows that the CX600 is even more capable of doing so and the numbers support that.
you could be right. however an OC'd ant is drawing about 400 watts to have a 500w PSU at 80% of it's limit is no bueno. by crobar, i meant to push it beyond its limits or to failure. my 1300 PSU turned out to be faulty (blown cap). the 600 still works well, just not well with my ant. that has been my experience...YMMV.