We are going to be focusing on the notch in the IHS.  In that notch you will find two lines of numbers.  The bottom line is where we want to focus.  Actually, it's just the last two numbers that we are concerned with.  Some theories say it's the last four numbers, but the one I'm spreading is just the last two.  Obviously, the last two digits have a range of "00" to "99".  The theory is that the closer these numbers are to "00" the better overclocker you will have.  The reason behind this theory is the position on the wafer.  "00" represents the closest to the center of the wafer and "99" the furthest away from center.  The center of the wafer represents the better of the batch.  Now in my very limited experience with this theory, the few CPU's that I have looked at have actually had a lower VID with the lower number and have actually overclocked better.  But as I stated, I have limited experience with this and have tested fewer than 20 CPUs.  So, my results could have been purely coincidental.  It's a theory, so you can try it for yourself and see how it works.