That guide is a generic guide to overclocking the Core2 chips. All Core2 chips behave the same way. What differs is how the motherboard acts. Some motherboards are great overclockers. For example, a lot of us really like the Gigabyte motherboards. Some models and brands are poor overclockers. ECS generally falls in that category. Unfortunately so do many Intel boards.
Many Intel motherboards, including yours, are designed for stability, not performance. The DG31PR is one of those boards that has what is called a locked BIOS. You have little access to performance enhancing BIOS settings.
Google "DG31PR overclock" to see what I mean. You may get lucky and find someone with a Windows OC utility that will work for you.
You may be out of luck. The DG31PR