I saw some 4890s still available at markets here
however, can a Sapphire 5770 Vapor-X overclocking beat 4890 or just be at its level?
i know all the goodies with the 5770 over 4890 but the 4890 performance is just great
also, will Athlon II X3 440 bottleneck either?
Well 4890 runs faster than a 5770 but 5770 runs cooler,quieter and has less power consumption + it supports DX11,eyefinity etc.if you play at a resolution like 1920x1200 or higher then go for the 4890,otherwise a 5770 can handle games fine on lower resolutions.
And you will be fine with that CPU
you will be able to overclock the 4890 by about 50mhz on core and 50mhz on memory at stock voltage.. I have heard that the 4890 has a lot of overclocking headroom. I've overclocked my XFX 4890 and loving the performance.