I tried to use some H/W test utilities to check chipset model, but the utilities reported the chipset is not Ultra model. Why?
Based on product specification, the board you have does come with nFORCE 3 Ultra chipset, not nFORCE 3 250 chipset. We have confirmed this symptom with nVIDIA. This is because nFORCE 3 250 series chipsets use the same device ID and cause wrong H/W detection report.