Yeah, that's the thing about overclocking. Being careful and researching first about your specific hardware. My pair of GTX550Ti's are the Asus DirectCU II version for the simple reason they have excellent coolers on them. Before the 3xx.xx drivers I was easily holding a 1050Mhz overclock on both GPU's without temperatures breaking 63C. That was stock voltage and a custom fan profile, and to top it off that's from 910mhz. Quite the gain for a SLi setup.
As for the G860, all of those Pentium chips like that, and even the i3's are some of the toughest chips I've ever seen. I don't think it's possible to kill an i3/Pentium CPU anymore LOL They might not be the fastest out of the crowd, but they definitely are high performance for their price.