OK guys,

I'm sure the answer's all ready in here, but don't quite have the patience to read all 15,000 posts.

If you're buying MR11 bulbs for building your own light or replacing burn out ones, is there any meaning to the phrase "high intensity"? That is, are some halogen bulbs more efficient than others? If so, what is the most efficient halogen bulb out there? Regretfully, I bought a bunch of bulbs 5 W 6 V MR11's from 1000bulbs.com thinking they were all the same.

When applying a greater voltage to a bulb to obtain more performance at the expense of the life, how do you calculate the expected life for the increase in wattage?