You may have to run some games on medium or lower settings, depending upon your screen resolution.
This is a link to see if your computer will run a program -- AFTER it is built. I have listed World of Warcraft, you will find a list of games to chose from below the main info screens [just scroll down a little to find a list of games to chose from].
It does give suggestions as to Minimum, Recommended, or Optimized score pass, but not always, some games list limited suggestions.
The site
DOES give suggested hardware for each game before running the test.
Scroll down and you will find a list of games to chose from, there are many and seem to be in order of release.
http://www.yougamers.com/gameometer/10132/