Did you make sure the heatsinks were tight? Sounds like heat issue.
I have not taken any of my S3s apart. Is that what you are suggesting? The temp is always under 40C.
That's what BitMain will recommend doing is taking off the heatsinks and reapplying the paste. I've got an undeperformer with a "-" asic, so I'll start there first. My temps are the same as yours and I only get 410 now.