I don't bin chips, so the string performance is pretty much luck of the draw. Nothing ships that isn't tested for 550MHz at volt setting 4. Performance above that is not guaranteed. I've had some test pods max near 900MHz and some at 775. It all depends on how weak is the weakest chip in the string.
No worries, I just got them up and running today and I've got all four on voltage setting 5. They've all re-targeted below my 588MHz and only one of them is below 550MHz. I'll keep an eye on it for the next 12 hours or so to see if there are any changes. I'm not super concerned about it.
so what is the make and model of the psu?
Its a Bitmain APW7, the fan screams right from the get go. It has a rating of 1000w at 83.3A (or at least thats what it says on the side) so I should be fine there.