question on processors

I am thinking about getting a new computer before too long. Mine is about 6.5 years old and I want to get a new one and save the one I have as a back up. It is a Pentium 4, 3 GHZ.

I am looking at computer specs and trying to decide on a processor.

As I understand it dual processors make the computer faster because tasks are split between the processors. Does the OS take card of that - does it automatically split the tasks out to the 2 (or 4) different processors?

Also, a lot of the dual processors I looked at have a speed a little less than 3gh. If you are running an application that is processing intensive - might that one task actually run slower? If you shut down everything to run a virus scan - might that scan actually run slower?

Just not sure how to compare how the speed of the dual processors would compare to the speed of a single process - when the speed of the dual processors is less that the speed of the single processor.

Hope this makes sense.

Fay

If I'm thinking right, dont hold me to it, duel, quad, etc. just means you can run that many applications easily without switching back and fourth. YOU CAn run more than one on a single but the power of it switche sback and fourth. So yes a duel can be slower i think repa im sure will have the right answer.

Here's a good explanation of dual core vs single core processors:

http://www.wisegeek.com/what-is-a-dual-core-processor.htm

It should be noted that to utilize a dual core processor, the operating system must be able to recognize multi-threading and the software must have simultaneous multi-threading technology (SMT) written into its code. SMT enables parallel multi-threading wherein the cores are served multi-threaded instructions in parallel. Without SMT the software will only recognize one core, and you might experience slightly slower processing speeds than with a single core processor. If you have a lot of older applications, they probably don't have SMT written into the code.

wwe,

Thanks for your input.

Fay

No problem

was my answer completely wrong?

Repa,

Thanks for the infromation and the link. I read the information at the link but still have questions. I was getting ready to post those questions last Thursday when I lost power due to the ice storm. I'll come back at a later time and post those questions.

Fay

Repa,

I am just now getting back to this. I was trying to post some more questions when I lost my power a while back.

• I would think that both Window-7 and Win XP support SMT - is that correct?
  
• If you have an OS that supports SMT but apps that don't, will the OS still make use of the dual cores by executing some apps on one core and other apps on the other? For instance would it perhaps run monitoring software on one and other things like word processing etc. on the other?
  Or if the OS support SMT but the apps doesn't - does that mean the dual cores are useless?
  
• If you have an OS that supports SMT and an app that support SMT - does that mean that the app it will itself make use of both cores while it is executing - running some instructions on one core and other instructions on the other?
  
• How do you find out if an app supports SMT - for instance AVAST, ADAWARE etc.
  
  

I want to try to make a good choice when I get another computer. I expect to have it quite a while.

Thanks,
Fay

Fay, see if these 2 articles answer your questions.

http://blogs.amd.com/work/tag/multithreading/

http://arstechnica.com/old/content/2002/10/hyperthreading.ars

This is my understanding of multi-core processors and SMT from what I've read:

SMT (ana hypertheading) allows more than one thread to be executed by a single core (CPU), so you could have several threads from a single application running simultaneously in a single core, and several threads from several applications running simultanously in several cores, which, of course means that several programs can be multitasking simultaneously.

For more than one thread per application to be generated, the application itself must have SMT written into its code to enable parallel multi-threading wherein the cores are served multi-threaded instructions in parallel. Without SMT, the software will only recognize one core in a multi-core system. However, even though a single program might not be multithreaded and can use only 1 core, Windows is multithreaded, which means that while 1 program is using 1 core, another program can use another, and so on.

Resource intense SMT applications can cause bottlenecks and slow throughput in competing for core resources. Microsoft and some others often recommend that you disable hyperthreading because it frequently degrades performance and proves unstable. The solution to faster processing is more cores.

Don't know how you know which applications have SMT encoded and which don't.

Reap,

Thanks for the inforamtion. I'll check out the links and re-read later whent I have more time.

THanks again,
Fay

Repa,

I just read the 1st article. Started looking at the 2nd one but it is a bit to long for right now, but I read enough to know I definitely want to come back and read it when I have time to read and digest.

I was confusing SMT with using of mulit processors. So you really don't need SMT for Windows to make use of the dual processors? My current computer has hyperthreading but I think I disabled it.

I am still a bit confused as to how to compare speeds (maybe the 2nd article will help with that). For instance I have 3G Pentium 4. A lot of the dual processors that I looked at were under 3G - maybe 2.8 etc. So I was wondering if some of my apps might run slower.

Maybe I am worrying about it too much

Again thanks a lot for the information.

Fay