The standard cards will feature a 850MHz core and 975MHz (3900MHz) GDDR5, while overclocked versions will offer a core clocked at 900MHz with 1000MHz (4000MHz) GDDR5 memory.
XFX has also phased out several models of Radeon HD 4890 OC Edition, including XT Edition with 875MHz core clock and XXX Edition with 900MHz core clock, while the memory clocks remain as 975MHz.
It’s believed that there’ll be even more OC editions of Radeon HD 4890 to compete with GeForce GTX 275.