Brands can make a bit of a difference in how long the thing will last. Sometimes the cheap ones are fine sometimes they break after a year or a day after your warranty expires
http://www.techpowerup.com/gpudb/ go to this link and u can choose specific cpu and gpu as per your reqs. it gives every small detail about cpu and gpu so you would know what u r actually getting instead of just getting confused by the series name. check prices from some other source and per ur budget choose the best combination possible.