haswell has an improvement of about 10% over ivy, but this cpu comes with 200mhz more than its predecessor, the i3 3240 @ 3.4ghz. so the performance increase is higher.
compared to the athlon, the i3 has better single core performance, due to its higher IPC, has HT, a small L3 cache and lower power consumption.
the amd counterpart has a higher clock speed (3.8ghz vs 3.6ghz), 4 cores... and i can't think of anything else to be honest. maybe, being it a 4 core cpu, it'll handle a bit better all those games with huge maps and an infinite number of players lol...
there are not many benchmarks out there. has anyone laid their hands on the previous generations of these cpus and can tell what pro and cons are of one over the other?
last but not least, which gpu could be the best match for either? i was thinking about the hd7870. what about you? is the 760 ti too much?
EDIT: i almost forgot, the 760k be has an unlocked multiplier, which will shorten the performance gap, if any.
EDIT2: one more thing, i would like to play at 2560x1080, yeah I love those 21:9 monitors.. would a 7870 handle the resolution? I don't mean max out, just make it pleasing and smooth..