1.OEM is identical with retails without the fancy box.
2.QS is short for quality sample, it is the best version of Engineering sample,identical performance as retail CPU ,we provide 1-3 years warranty. important different with ES CPU is 1, QS show CPU model in BIOS and windows computer property.ES does not show CPU model, only speed . 2 QS has same stepping as OEM, ES has earlier stepping than QS and OEM.
ES, is engineering sample. theroatically not as good as retails,eg however is very close to the final production, good value. we guarantee stability and performance.