Ti 400/500 vs. 550/667 - Memory BANDWIDTH difference!?

luke etyrnal at ameritech.net
Sat Nov 23 10:48:36 PST 2002

Hello Fellow Mac Speedsterz...

I bought my powerbook for ONE thing:  MUSIC PRODUCTION

When the Ti 400's and 500's came out it decided by many that the power  
book had finally come-of-age for portable music production - enough  
proc. power and drive space etc...

I was thrilled!  So i waited for the next gen. machines (not going to  
buy first rev.) then the Ti550 and 667's were announced...  i bought.

and I both experience and read that the 550's and 667's are NO  
comparison to the 400's and 500's...

I feel like Apple was misleading (or elusively-leading) in their  
advertisement of the next gen. of machines.  The machine i bought which  
should be faster than the prev. models is actually considerably slower.

I read the following and was wondering if anyone will comment on this?


> Memory Bandwidth and Logic Audio Tests: (from the 12/14/2001  
> www.xlr8yourmac.com news page.)
> Regular readers here know that since the first 7450 G4 based Macs were  
> released there's been comments on much much lower than expected memory  
> bandwidth compared to the G4 7400/7410 CPUs. (The 7410/7400 G4s had  
> dramatically higher bandwidth - nearly 100MB/sec more in some tests.)  
> A first report on the 2.1 stepping 7450 seemed to show this was fixed,  
> but tests I've run since then show the rates are still much lower even  
> with 2.1 rev 7450s compared to external L2 cache/shorter pipeline  
> 7400/7410s. (There have been discussions on this many times since the  
> beginning of the year about compiler optimizations, etc. which is too  
> long to discuss here). My comments above noted my PB G4/400 had much  
> higher memory bandwidth than the PB G4/667 (2001).
> A reader sent an email tonight on why the much lower memory bandwidth  
> of the new PowerBook G4/550 and G4/667 models (compared to the PB  
> G4/400 and /500 models which use the 7410 CPU) make the earlier  
> Powerbooks a better choice for Logic Audio.
> (Update: I've added a reader's results with the 2002 PB G4/800 to the  
> listing below. For other PB G4/800 2002 model tests, see this > article.)
> " Hi - though you might like to have this info - I and a few others  
> have been doing some testing on the old Powerbook G4/500 vs the new  
> 550 & 667.
> Memory bandwidth on the 550/667 is a *lot* lower than on the 500 - the  
> new 7440 CPU is to blame, not the amount of cache. The older 7410 CPU  
> is better - we've measured memory bandwidth at 230MB/sec on the  
> 400/500, vs 145MB/sec on the 550/667.
> [Again this is not news to regular readers here and was noted in my  
> earlier comments above comparing the PB G4/667 (2001) to my PB G4/400.  
> It's good to see an example of where this has an actual applications  
> impact.-Mike]
> What this means is that for audio use, where many simultaneous  
> realtime DSP processes are required, the old PBG4/500 will perform  
> significantly *better* in many operations than either the 550 or the  
> 667.
> A simple test using simultaneous stereo Platinumverbs in Logic Audio  
> 4.7.3:
> *	PB G4/667 (2001) - 9 platinumverbs
> *	PB G4/550 - 7 platinumverbs
> *	PB G4/500 - 13(!) platinumverbs
> *	PB G4/800 (2002) - 18 platinumverbs
> (He later said his Umax S900 w/G4 at 473Mhz managed 6 Platinumverbs on  
> 67MB/sec memory bandwidth.-Mike)
> We didn't test the PBG4/400, but it's likely that will also outperform  
> the 550 and perhaps even the 667... Memory bandwidth is the key.
> While end-of-stock, secondhand, or refurbished PBG4/500 and PBG4/400s  
> are available, they are a *much* better choice for audio work than the  
> new 550 or 667... The 400/500 also have the advantage of allowing the  
> processor speed to be reduced which increases battery life &  
> eliminates fan noise - the 550/667 do not allow this I believe.
> John Pitcairn "



For an evening of thought-provoking background music...

                              etyrnal at ameritech.net

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