Nope, even if it can barely cope, you should be using a better psu for hardware of that quality
better as in higher watt, i always have an overkill PSU for safety and upgrades
Exactly this, if we had more info from op it would be alot easier to say he needs this much power to run his system.
I have a very similar setup i5 6600k and r9 290, when gaming I get up to about 375-400 watts so I would not do the 450w. Micro center is having s sale on the one that I have and I have no compaints
http://www.microcenter.com/product/457306/CX_Series_CX750M_750_Watt_ATX_Modular_Power_Supply
The easiest way is to just read the reviews of the gfx card, they all say maximum power draw is about 400w. Hence a 450w should work.
Short answer no, get a 700w EVGA G2 or superflower 700w.
Long answer, yes by the skin of your teeth but your PSU wont like it.
No. Why risk your hardware on a relatively cheap component? (compared to the cost of the system).
700W at least.
No