[G4] MDD L2, L3 cache switch off at startup. Does it matter?

Charles Schneider schneidr at umich.edu
Thu Oct 11 05:37:00 PDT 2007


Do you mean the hardware section of System Profiler instead of system  
preferences?

I have the same machine, here is my hardware section of system  
profiler.  Firmware is 'Boot ROM Version'

Hardware Overview:

   Machine Name:	Power Mac G4
   Machine Model:	PowerMac3,6
   CPU Type:	PowerPC G4  (2.1)
   Number Of CPUs:	2
   CPU Speed:	867 MHz
   L2 Cache (per CPU):	256 KB
   L3 Cache (per CPU):	1 MB
   Memory:	1.5 GB
   Bus Speed:	133 MHz
   Boot ROM Version:	4.4.8f2

Do you have any processor upgrades?  How did you switch them to their  
normal settings?



charlie



On Oct 10, 2007, at 10:30 PM, dkmnow wrote:

> Pretty low-priority question, but here goes:
>
> First, the system details:
> G4 Dual-867 MDD Power Mac
> 133mHz bus, 512mb DDR2 PC2100 RAM
> Running OSX 10.4.10
> Firmware version unknown.
>
> Okay, this may be a Tiger thing, but I figured it was
> worth asking.  I know virtually nothing about what the
> L2 and L3 cache do, but I have noticed that the
> Hardware pane in my System Preferences shows that L2
> and L3 are set to "none."  I have tried switching
> these to their normal (rated) settings, but after
> startup, they always revert to "none."  I tried this
> on 10.4.8 and .9 as well, with the same result.  I'm
> not having problems of any kind with this machine, but
> for obvious reasons, this just doesn't seem right.
>
> My first thought would be firmware, but I'm reluctant
> in this case.  If I were having "issues," yeah.  But
> am I right in thinking there would be very little gain
> in performance simply by inducing the L2 and L3 cache
> to remain on?
>
> My general and rather vague understanding is that, at
> least in the case of the G3 iMacs, the chip where the
> firmware lives can only be rewritten a limited number
> of times, and if you exceed that limitation, you're
> toast.  I have no idea if this applies to this
> machine.  Also, I bought this machine second-hand last
> year, so I have no idea how many times the firmware
> might have been rewritten, if at all.  And from what
> I've seen on the web, the wiser contributors seem to
> agree that updating firmware is pointless at best
> unless you're actually having problems known to be
> addressed by an update.
>
> So, there it is: What will keep the L2 and L3 cache
> running -- and should I care?  :-p
>
> Also, is there a way to check my existing firmware
> version without getting too technical?  It doesn't
> seem to be listed by the System Profiler.
>
> Thanks, and best wishes to all.
>
> David K. March
>
> [report on recent cooling/airflow mod to follow shortly]
>
>
>
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