Process nodes

[Daemas]

What nodes are motherboards built at? I would assume 45nm since we've been there for so long. How long until we start to see boards built on 32nm? I would hope by the time Sandy bridge is out?

What are the pros/cons for moving down a process node? Obviously less silicon used, but with connectors (like SATA, internal USB headers, etc) remaining the same size, there's really only so far we can go right?

anyway, just some things I was thinking about.

 

[drescherjm]

This question does not make sense at all. Process nodes are about transistor gates not about motherboard wiring.

there's really only so far we can go right?

In some areas the wiring on the motherboard will be getting thicker not smaller.

 

[Proneax]

Perhaps you mean chipsets?

The motherboard itself is a multi-layer printed circuit board made of alternating layers of copper and some type of fiberglass or similar insulator. Look it up on wikipedia. The line-width of the copper traces on these boards is not decreasing.

The ability to decrease line widths is only meaningful when your circuit travels a very small distance (say 1 micron), because the smaller the diameter of the wire, the greater the resistance per unit length. So for 32nm chips, the transistors are made @ 32nm, but even the first level of metal wiring is more like 70+nm. There are something like 10 levels of metal wiring, and many of these levels have line widths measured in microns (1 micron = 1000nm = 1/1000th mm). Again, it has to do with resistance.

Chipsets are generally 1-2 process nodes behind. While the newer process nodes generally reduce the cost "per transistor" there is a desire to offset capital costs by continuing to use fabs that were designed for a given node and cannot be updated to run the smaller process. With the memory controller now on-package / on-die, there is no performance motivation to go to smaller process nodes for the chipsets either. So the current intel chipsets are done @ 65nm to get extended use of the 65nm fabs. If it continues to be economical for them to make chipsets at this node, they may continue to do so for some time.