honestly, I wouldn't go with a benchmark bcs if you only get a higher score in benchmarks it's pointless
start an application (like unzipping a large file or converting a video to another format) or start a game and run it with minimum eyecandyA/graphic settings
run it once OC'd once not OC'd
depending on the time difference you need / fps difference you're getting you see how much overclocking does for you
i can't test min/max fps on my playable games, i play lol/csgo [not constant framerate, cause the scenes get more or less difficult to proccess for my hardware]
on csgo it's pretty easy.
you join on an empty server without bots or go into practice and look at your fps there
one time with one time without OC and measure the difference at certain fixed points