For just a 4.3ghz OC I have to agree with 1LiquidPC, 102mhz BCLK should not be a problem at a 43x multiplier, now 50x multiplier YES! but 43x no?
Even though if the BCLK is manually set, it should stay exactly where it is set and should not fluctuate, unless you are using some type of Auto Overclocking software?
So please answer 1LiquidPC's question, "What OC settings are you using? "