I have two S3's, received last Friday. One of them hashes at 440GHs at stock speed (218.5), so I'm fine with it; however, the other hashes at 400 GHs at stock. I've been trying different things like putting it on a different psu's like ATX, Dell/HP server, but nothing helped. I'm taking notes on different clock speeds on this one:

Frequency     GHS(avg)      Temps       HW            Watt (Kill-A-Watt)     ASIC Status
----------     ----------     -------     --------     ------------------     ----------------------
250              487.26          41, 41        2             428                         Chain#2, 1 "x" on the far right
237.5           423.55          39, 37       38             367                         All OK
225              422.69          39,36         7             364                         Chain#2, 1 "x" at 2nd position & 1 "-" at 8th position from left
218.75          403.58          40, 38        0             355                         All Ok

After editing the asic-freq file, a reboot command was issued. All readings were take at 30 minute mark. PSU is a Dell Server Power Supply 750W. All 4 PCI-E cables are plugged in, even at stock frequency.

Yes, it took me over 2 hours to finish writing this post.  

I'm setting the frequency at 250, seems to be the sweet spot for this S3.

At what frequency would you run this at? Why?