VIA P4PB is performing pretty well at DDR333 mode but it appears to be slower than the P4X333 reference sample. I can't confirm whether the retail version of P4X333 is slower than the reference sample because i don't have the reference board with me but it appears to be so. Perhaps VIA didn't really optimize the performance of their retail boards to match their reference sample because the boards will be mass shipped to consumers and stability is their top priority.