Please remember that any mention of competitors, hinting at competitors or offering to provide details of competitors will result in an account suspension. The full rules can be found under the 'Terms and Rules' link in the bottom right corner of your screen. Just don't mention competitors in any way, shape or form and you'll be OK.
If it a quality 450W even a 290 reference card might be fine to be fair. Playing BF4 with 2x290 Pro cards at stock (975/1250 - so small overclock from typical 290) and i pull 500-550W from the wall with my i7 at 4ghz.
I guess you never owned a small PC case that has high power Components in it then...id go with a 780 tbh. wouldn't go with stock anything.
290 is too long, 770 or 780 are the GPU's are will use.
Thanks everyone.