For the most part you cannot overclock on the B85 chipset. There was a few cracked bios around if I remember but these were designed for the g3258 and its lower power draw. Most b85 boards do not have the power delivery to handle an overclocked quad core.
Have you looked at a lower end z87/97 board or even a used one. I saw some used boards on eBay for 50 euros.