EVERYONE KNOWS that Intel's new Socket 775 (LGA775) simply sucks, after all, it has to, could 1,000 people on 100 message boards all be wrong? It is something new and different from Intel, who has none of our best interests at heart, it simply must be a conspiracy. It is fragile, expensive, and does nothing that the old socket would not do. If you look at it cross-eyed, or god forbid, put in a CPU for a fourth time, the board will simply catch fire. Nothing good comes from it, trust the friendly anonymous posters, none of which have an axe to grind, honestly.

Put away the tin foil hats people, it isn't any of the above. I read the same things you probably did, and talked to some of the same people you read about, and several more. I have heard just about every conspiracy theory out there, and I noticed something odd, no one asked Intel if they were true. What is even more disturbing is that amidst the armchair quarterbacking, or at least armchair Electrical Engineering, no one bothered to ask the question "Why is LGA775 better than s478"?

Guess what, I did, and found out a few things that tell me that LGA775 is indeed better than s478, and is the way of the future. I talked to a member of the CPU applications team for desktops to find out more about the socket, what it does, and what it does not do. Lets just start out with a little history before we jump into the topic at hand.

Most of you have never seen anything other than a CPU with lots of pins on the bottom, but they exist. When I first started out in computing, CPUs were generally in DIP packaging, that is two rows of pins, one on each side of the CPU. These were placed in holes in the motherboard and soldered in, but there was the occasional socketed one. On the good old Atari ST, people made a brisk business of selling sockets for the original 8MHz 68000.

Then came chips with pins on the bottom. I looked around at the time and the world didn't end when they were introduced. There wasn't even a major earthquake caused by the addition of the ZIF socket in the late 486/early Pentium days. While the mere mention of Slot 1 or Slot 2 can make an Intel engineer involuntarily twitch, it was a short-lived idea. Sockets reigned again shortly after that, and the world was a happy place.

Then came LGA775, and it broke new ground, or at least looked mighty different from the things that came before it. Once again, people cowered, covered children's eyes, and ran for the safety of the television, tin foil helmets protecting them. The problem is that the socket differs in far fewer ways than you might think, and the ways it differs are probably not anything you are aware of.

The first major difference is the pins, or their lack. They have little metal fingers on the motherboard, and the CPU itself is a PCB with pads that the fingers contact. These fingers, called contacts, are more or less the same type of contact that was in the little plastic sockets of old, it's just that you can see them now. The next part, and the part few know about is the electrical routing. Intel did not just change the the number of power and ground pins to allow better power distribution, it also changed how the power is routed to the CPU across the motherboard. There are come very big differences here. Lastly comes the physical layout, both in terms of the socket, and its immediate surrounding area. Each of these things makes LGA775 better than s478, and we will take a look at them in reverse order.

First is the new retention mechanism. If you remember, the old way was to put a chip in the ZIF (zero insertion force) socket and close the little lever on the side. This clamped the chip in and held it down relatively tightly. If you tried hard enough, you could pull it out, there was no locking mechanism to keep it in place. You then put a large part of a battleship hull, known in the industry as a heatsink, on top, and clamped it down with a clip that locked it in place. On top of this was a fan that could lift the remaining parts of that battleship off the ground. It was big and heavy, had clearance problems, and was a bitch to put on. It could fall off in the shipping process. The thermal interface material could cement the CPU to the heatsink, and pull it out of the socket if the heatsink fell off. Since the heatsink was the only locking mechanism, there was nothing other than friction to keep the CPU in the socket. Not a good thing from a physical perspective, and having a hunk of copper weighing the better part of a pound rattling around lose inside the case was even worse.

Intel learned from these problems, and designed the physical retention mechanism for LGA775 to address them. The first is the most radical break, the heatsink no longer provides the only mechanism to hold and lock the CPU in place. Look at the picture below, the metal rim holds the CPU in place with enough force to allow the fingers to contact the pads, and the little metal arm provides the locking mechanism. Even without a heatsink, you can't pull the CPU out of a LGA775 socket.

This allows the heatsink to be put onto the chip with much less force, it simply needs to contact the CPU hard enough to make the thermal interface. If you have ever clamped a heatsink onto a s478 board, you can often see the board flex under the strain. This is an engineered behavior, so it is nothing to worry about, but it can be unnerving anyway. That behavior has also been banished to the nether realm of 'the old way'.

That brings us to the area around the socket, it has been defined with an eye on more flexibility. This time, there are more solutions available to motherboard designers while allowing them to stay in the spec. With the coming of the P4, you started to hear about certain brands of heatsink not fitting on certain mobos, and capacitors leaning precipitously when a heatsink was put into place. Once again, Intel learned from past problems and defined the area around the CPU in much more detail, and paid special attention to those caps. They left enough clearance so that an industry standard low profile bulk capacitor can fit under the heatsink. This allows for the caps to be placed as close to the socket as possible, which gives you cleaner, more precise power, and more stability. If you look closely, you can see one of the capacitors under the heatsink, it is the blue and white part. Also to its immediate left is a US Quarter for size a reference. µ [Part II to follow tomorrow]