Asrock boards in general are pretty good for overclocking, but I find that asus, gigabyte, and msi boards are usually better in terms of stability. Overclocking will come down to your particular chip as well as the cooler you are using. If you are going to oc you are going to want an aftermarket heatsink. I don't know what you have available, so a list of what you can get your hands on would be nice. As long as you aren't going for some crazy overclock then the asrock board should be fine. x16/x4 isn't preferable for cf, but swapping motherboards is a total pain and I would recommend that you spend a little bit more for a board that can do at least x8/x8.