[G4] Single or Dual??

[Mike Tweedie]

Also, using the utility from PowerLogix, found here;
http://powerlogix.com/support/agp_dual_compat/index.html

I can in fact add a Dual CPU to the mobo.

Mike

> Excellent post Phil, thank you.
> 
> I do a lot if image editing, and now spend lot of time restoring vintage
> photos. Next step for me is to start stitching some video together, but
> nothing major.
> 
> Though I don't specifically need dual, I will be using an OS and apps that
> can leverage the extra CPUIs. Just not sure it's worth the extra dough at
> this point.
> 
> Thanks again.
> 
> Mike

> 
>>>> Date: Thu, 08 Dec 2005 16:48:19 -0500
>>>> From: Mike Tweedie <mac at springerlabs.com>
>>>> To: "A place to discuss Apple's G4 computers."
>>>> <g4 at listserver.themacintoshguy.com>
>>>> Subject: [G4] Single or Dual??
>>>> Reply-To: "A place to discuss Apple's G4 computers."
>>>> <g4 at listserver.themacintoshguy.com>
>>>> 
>>>> I just picked up a G4 Sawtooth 500Mhz ... it's time for a new
>>>> processor.
>>>> 
>>>> [snip]
>>>> 
>>>> Single or Dual?
>>>> 
>>>> Looks like I can get a dual for just a bit more than a single, see
>>>> here;
>>>> https://eshop.macsales.com/item/PowerLogix/PF47D1200DA/
>>>> 
>>>> What are the groups thoughts? 1.2Ghz Dual or 1.8 Single?
>>> 
>>> Having observed CPU usage in my Dual 867 MDD using the CPU Monitor
>>> part of Activity Monitor, I would say that, presuming you're
>>> running OS X (Panther or Tiger, and probably even earlier
>>> versions), you'll get close to 100% usage of the dual processors,
>>> so that a 1.2 GHz Dual will be almost as fast as a 2.4 GHz single. ...
>> 
>> Wouldn't it be nice if it were this simple. A single processor will
>> always be as fast or faster overall than multiple processors that sum
>> up to the same speed because it doesn't have the overhead associated
>> with distributing a task between the multiple CPUs. To take advantage
>> of multiple processors an application has to be properly multi-
>> threaded, and there's no guarantee that the applications that you
>> care about or might care about in the future will be. Put another
>> way, multi-threaded applications always run measurably, and often
>> noticeably, slower on multiple processors than they do on a single
>> fast-as-the-sum-of-the-multiple-processors machine.
>> 
>> So why would you want multiple CPUs? There are a couple of scenarios
>> where multiple CPUs make sense.
>> 
>> The most obvious case is where the fastest CPU available isn't fast
>> enough for your needs. In this case you have no choice but to figure
>> out how to divide the task in question up between multiple processors.
>> 
>> Two, for whatever reason sequential processing of applications is
>> unacceptable. For example it may be required that you get a constant
>> flow of data from multiple applications and the OS's scheduler can't
>> or doesn't divvy up processor time acceptably. Or it may not matter
>> how fast a set of multiple applications run, but the applications are
>> time sensitive enough that they need dedicated resources such that
>> they are always ready to run. Multiple processors make it much more
>> unlikely that any single application will take over a machine and
>> make it unresponsive - particularly to interactive use.
>> 
>> I would always prefer to have a single processor that is twice as
>> fast as 2 dual processors for a desktop machine. I rarely run more
>> than one important task at a time, I want that particular task to run
>> as fast as possible, and I'm willing to trust that the OS's scheduler
>> will keep the machine reasonably responsive for interactive use.
>> 
>> Mike's case isn't as simple as the one that Aaron posited. As Aaron
>> pointed out there may be significant differences between the CPUs in
>> question. This makes it impossible to choose between them without
>> knowing what Mike intends to do with the machine and how the
>> performance of the CPUs compare. Note that some of the recent faster
>> clocked G4 processors have smaller caches and different enough
>> designs that they are not as fast as you might expect them to be, but
>> they run cooler which may be important to some situations.
>> 
>> Also not that early Sawtooths are not multi-processor compatible.
>> 
>> 
>> Phil
>> --