when will intel start incorporating SOI in their cpus?

[dannybin1742]

i've been wondering this for a while.

SOI allows a cpu to run cooler and dissipate heat better (?) so why has intel not incorporated this into their chips, it seems logical especially with the new prescott cpus (more that 100W heat dissipation apparently). i wonder how much farther they could push .13micron p4 with SOI- then heat would be a smaller issue

 

[dew042]

as i always understood it SOI advantages were theorectical mainly and haven't been field proven in a CPU environment. I don't think AMD has fully rolled it out yet either has it?

dew.

 

[MDE]

They are using it on Opteron\Athlon 64 right now.

 

[Wingznut]

The short story is that SOI is not without its flaws... Most notably are the significantly higher cost per wafer, and the higher amount of defects in the wafer (both before and during processing.) Rumor has it that the move to SOI has been the catalyst to many of AMD's delays with the K8.

Intel's thinking is that partially depleted SOI does not have enough benefits to outweigh the negatives, at this time. (But check back when fully depleted SOI becomes mature.)


And actually, SOI does not help the cpu to dissipate heat. It can help the cpu to run cooler, mostly due to reduced capacitance.

Also, power and heat aren't really issues with making cpu's faster... It's the gate leakage in the transistors that makes things difficult.


Sysopt.com has a pretty decent article about SOI, written in (mostly) "everyday" terms. It's a little dated, and it doesn't go into the drawbacks much... But it's still a pretty good read, to get the gist of SOI.

 

[bgeh]

wingznut, what is strained silicon actually?
is it something like SOI?

 

[Wingznut]

Originally posted by: bgeh
wingznut, what is strained silicon actually?
is it something like SOI?

No, it's quite different.

SOI is a silicon wafer with silicon dioxide (an insulator) built into the substrate.

Strained silicon is a wafer in which the silicon lattice is "stretched", allowing the electrons an easier "path" to flow, which becomes a faster cpu.

Anand actually explained it quite well in this article.

Purely hypothetical numbers here: If you built the same cpu on a bulk (typical) wafer and on a SS wafer, the cpu might run at 3.5ghz on the bulk wafer but it would run at 4.0ghz on the SS wafer.

 

[dannybin1742]

damn thats cool

has anyone thought of soi with strained silicon?

 

[Wingznut]

Originally posted by: dannybin1742
damn thats cool

has anyone thought of soi with strained silicon?

It's definitely being worked on.

 

[zephyrprime]

I think it's inevitable that they will. It's just that being the first adopter is frougt with problems. I think the prime reason the K8 is so delayed is because of problems with SOI. Intel just figured that it didn't need SOI quite yet and and it seems like they were right.