Will this board boot up even if i attached the chassis fan directly to the PSU?
Yes... if everything else is in order
Or do I need to attached it directly to the motherboard's rear fan header?
No - a chassis fan is not necessary
Have you checked your specific RAM is compatible (these motherboards are very finicky in what will work or what won't)? Have you double checked all your connections with the manual. Have a look at Intel's no-boot wizard accessible from the support page for your board and see if that helps.
My Huntkey PSU says that it generates 18.0A.
Will i have to buy a new PSU?
I very much doubt it for the motherboard as thats a recommended value and is far from black and white. I've seen many 'over enthusiastic' PSU minimum system requirements from Intel and I very much doubt 2 amps on the 12 Volt rail would make a difference (as long as the PSU is actually performing to that spec).
What about the memory - as previously mentioned, these boards are picky for memory. Have you looked at the board specific memory page yet to see if it matches up?
Also I see here on the manufacturers webpage that the recommended 12 Volt rail capability is 25 amps just for your graphics card - THAT may make a difference but not being very experienced with these cards I don't really know - maybe someone else with one can comment? I assume you have plugged the graphics card into the PSU connector as well?