$799 Lenovo K450+ GeForce GTX 700 series cards rig = beat alienware desktops?

[the_rebrith]

Hey guys, I'm planning on invest approx. $1000 in a decent desktop for both gaming (crysis4, BF4) and study/programming.

Originally I had my eyes set on the alienware desktops, which is a bit above my price point but still OK. But today I just found out lenovo's ideacentre K450 is having a promotion for $799, for which you get i7 4770, 16GB 1600MHz ram, 2T 7200rpm HDD, integrated HD graphics, no discrete graphic cards. I'm thinking on swap the original psu with a 600W+ psu and add a GTX 680 or a even better video card. But I don't know if this could cause any overheating/noise/compatibility issues, so I'm eagerly looking forward to your input on this.

I'm kinda a newbie here, apologize in advance if any questions seems too obvious or naive to you. Be gentle... Thanks!

 

[the_rebrith]

And here's the k450 i referred to http://shop.lenovo.com/SEUILibrary/controller/e/web/LenovoPortal/en_US/builder.workflow:Enter?mtm-item=:000001C9:0000EA6E:&cid=us:cse:OAB9Cs:ca|dealmoon|57314032&CA_6C15C=1932091767&AID=10383968&PID=2165238&SID=no_refer&CJURL=http%3A%2F%2Fshop.lenovo.com%2FSEUILibrary%2Fcontroller%2Fe%2Fweb%2FLenovoPortal%2Fen_US%2Fbuilder.workflow%3AEnter%3Fmtm-item%3D%3A000001C9%3A0000EA6E%3A%26cid%3Dus%3Acse%3AOAB9Cs%3Aca%7Cdealmoon%7C57314032%26CA_6C15C%3D1932091767&PUBNAME=dealmoon.com&NID=CJ