The rough distinction is between very fast single core versus slower multi-core processing. Most games still only use a few cores so they profit from high clock speeds where tasks like video encoding when the software is written correctly can use the full range of processor cores which distributes the workload across many threads.
My old box and the one I am trying to finish use an unlocked 5820k 6 core and at 3.8 gig, it is faster than the 12 core that runs all core at about 3 gig so you pick what works the best for a particular task. As a dev box the 5820k is a better proposition but for large scale processing, the Xeon 12 core because it is simply faster on low thread count tasks.
When I get this new one finished, I will experiment with upping the clock speed as this particular processor is designed to be clocked up to the the safe temperature the cooling solution can handle. If you can keep it under 60c under full core load, it is safe and will last for years.
To add insult to injury, the new can I had delivered last night will not accept the board and cooler so at about 1 AM I ordered another case that I know will work with the board and cooler.