I think I have it narrowed down to a voltage issue. The old heatsink/fan had only a small 3-prong mobo connector; rotation/+12v/GND. The Volcano has that same connector, but it only has one wire (for rotation detection). It gets it's juice from another, larger connector; the 4-prong size you would use for your hard drive, case fan, etc. However, it only has 2-prongs, not 4. They must be the 12v and GND. You would think 12 volts is 12 volts no matter how/where it gets it, but who knows. The problem is it won't boot with the normal FSB speed of 133. It clocks to 1466MHz by going 11 x 133 FSB. At 1100MHz it's 11 x 100 FSB. The CPU voltage is 1.75v regardless. I'm assuming it is taking more voltage to run at 133. Maybe not. I have a 400w power supply. I unplugged a couple of case fans, thinking I was somehow maxed out on my power; no help. I put the old heatsink/fan back in and it works fine at 1466MHz, so it's not like I accidentally messed up some other component when I was in there working.
Maybe it is the way I had it seated. I see what you mean about the 2 'plateaus' on the heat sink. I thought I had it right, but I'll try again. There is not much room to play with though; the side clips don't stick out very far from the sides of the heatsink.
Rich