And i quote:
" The first conclusion is that the ATi Retail cards are better, this however is far from the truth. With a Voltmeter you can find out what the Core Voltage (Vcore) and the Memory Voltage (Vmem) are. The Vcore is approximately 1,65V with OEM’s while the retails get 1,75Volts of juice. This is not dramatic. Most OEM’s can be clocked to a 300Mhz core frequency without a Voltage adjustment, any higher however, requires 1,75 Volts. "
end quote.