SOI question

[OCn00b]

Ok, I admit it. When it comes to how a cpu works, I'm about as dumb as a rock. I've accepted it and am living comfortably with that knowledge now. What I'm curious about is what exactly is SOI. I mean I know what it stands for but what does it actually do. Is it supposed to improve performance? If so, how? Will SOI be of any help to overclockers? Basically any and all information is welcome. I just have one request. If you can explain it, please do so in a way that somebody with no knowledge of what you're talking about can understand. Thanks guys.

 

[Lord_MiL]

essentially the chips are now built on top of a layer of insulation which reduces the total volume of silicon in the chip and because of this, the transistors can charge/discharge faster and draw less current. This means a couple of things:
1. SOI chips use less power and are cooler
2. SOI chips can scale higher than the same chip on a typical CMOS design.

To understand more, it might help you to read this article.
HERE

Basically a transistor represents a 0 or a 1 to a computer based upon whether electricity is flowing through it or not. If the chip is made using silicon (as current chips are) then all of the silicon can hold a certain charge (this is called capacitance) By building the chips on top of an insulator and only using a very thin layer of silicon, less charge is needed to switch the transistor on and that smaller amount of charge can leave faster when the transistor is switched off.

 

[OCn00b]

That makes perfect sense to me now. Thanks for the explanation Lord_MiL

 

[hitechjb1]

Silicon-on-insulator (SOI)

SOI paper - A simple and clearly written article about silicon chips, traditional silicon process (bulk) and SOI, and the advantages of SOI on speed, power and soft error rate.

In addition, the article can serve also as an introduction to MOS, CMOS transistors, capacitance, scaling, ... in silicon chips, including nice illustrations and a cross-section of transistors in a SOI chip at down to 0.01-0.1 micron resolution.


Quote from the article:
"SOI technology improves performance over bulk CMOS technology by 25-35%, equivalent to two years of bulk CMOS advances. SOI technology also brings power use advantages of 1.7-3 times. IBM is currently working with many circuit designers and product groups that are designing with SOI technology. The company expects SOI will eventually replace bulk CMOS as the most commonly used substrate for advanced CMOS in mainstream microprocessors and other emerging wireless electronic devices requiring low power."

 

[rugbyroy]

wow you guys know your stuff. Nice posts.

 

[Pla]

This is very interesting knowledge.

I am very happy to see that there are people who are also inerested in the science behind the technology.


Thank you guys!

 

[james.miller]

These are exiciting times. With SOI finally making an appearence, we should see cpu performance rocket in the next year or so.

 

[ayoung]

What did u just say james???

Rocket?

Intel 3.06GHZ?!?!

AMD 3200+

What r u smoking?

What do u use that NEEDS anything over maybe a 1.6 or a 1600+?

The only thing that needs speeds like that are servers, graphic desiginers and Cad designiers... buy thats why they make "workstations" that have multi-procs'.

We are way tooooo far ahead of our software in todays times.

 

[james.miller]

in the grand scale of things, ayoung, a 3.06ghz p4 isnt that fast. if that kind of processing power can be had with a £40 xp1700, then its not really that special, is it?

Now i never said we needed that power (not yet anyway, 'you seen Doom3,Thief3 ect ect ect). But, it would be dmn nice to own one of those puppies.

Also, did you even see the pics of the Opteron server? it was only using passive heatsinks.........now thats impressive

 

[kaltag]

Who needs that kind of power??? Me and my folding bretheren (sp?)

edit: WOOT!!!! five stars

 

[Lord_MiL]

Sadly, I don't think that hardware is that far ahead of software. It could be, but it seems that the faster they build them, the sloppier programmers' code gets.
In fact, there's a law for this, called Wirth's law. It states that software gets slower faster than hardware gets faster.
I think that as long as companies continue to bloat their software with warm, fuzzy graphics and features that no one needs, then people will continually want faster computers. And you and I both know that Microsoft isn't planning a version of windows anytime soon that will be smaller or faster than its predecessor.
So, you are right, there really aren't many things today that require this kind of processing power (well except folding, SETI, and other positive efforts) it's the bloatware that causes us to need to upgrade to stay ahead of the game.
It would be awesome to be able to build a system today that was cutting edge and have it still be cutting edge in 6 months, but that's just not the way this industry works. They will continue to make things smaller, faster and (God help us) hotter as long as they can make a buck.

 

[AcEmAsTr]

A 1.2ghz with 32mb gfx card will run pretty much anything with all the eycandy turned either down or off, 256mb gfx really needed? doomIII only takes up like 80mb, yes having a 3ghz CPU is a serious boasting oppurtunity but is it really needed for general work/gaming?

 

[hitechjb1]

BTW,

The current Tbred is based on 0.13 micron BULK silicon process.

Whereas the Opteron and the planned Althlon 64 (ClawHammer) are based on 0.13 micron SOI silicon process. And is roadmapped to use 0.09 micron SOI down the road.

I.e. SOI is already faster than BULK as described by the SOI paper in previous post.

And 0.09 micron SOI process is also faster than the 0.13 micron SOI process with lower Vcore. That is, lower Vcore and faster.