I've been hearing of Epox NF4, 570 & 590 boards having issues with the SATA and IDE channels. Was the 2nd channel DOA? or did it work at one time? and just out of curiousity, have you updated the bios at all?
epox usually puts out a solid product & I personally know they have great support. so its possible you may just have a bum channel
overclock depends on the capabilites of these components:
CPU, mobo, ram, PSU and cooling.
if your new, the best thing to do it take it easy.
from the bios, just raise your fsb a bit (5mhz at most per increment)
then begin stress testing your cpu. I like prime95 myself (blended test)
you can keep doing this until your test fails or you can't boot into your O/S OR you can't get past the POST screen...etc etc...
then you have a bunch of options including voltage, lower your multiplier, ram timings..c... which I wouldnt touch without experience.
Its always best to learn by taking older, more importantly cheaper parts and experimenting.... this way you dont feel to bad when you accidently destroy something