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Old 26th July 2011
Ninguem Ninguem is offline
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Default Differences in processing in POWER CPUs.

I've noticed recently that building KDE4 on an iMac G4 with an 800MHz processor seems to be more efficient than when I built the same on a PowerMac G4 with a 933MHz processor. I'm curious as to whether it was an issue with the Quicksilver or if the iMac was built better.
Both processors are Altivec, load-store and fpu active with one being a 7450 and the other a 7455- if that makes any difference.
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Old 27th July 2011
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I'm from the x86 generation, so I'm not an expert, but aren't these machine PowerPC, and not POWER?

In any case, clockspeed is only one (small) metric of the overal speed of a CPU. See: http://en.wikipedia.org/wiki/Megahertz_myth
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Old 27th July 2011
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Quote:
Originally Posted by Ninguem View Post
I've noticed recently that building KDE4 on an iMac G4 with an 800MHz processor seems to be more efficient than when I built the same on a PowerMac G4 with a 933MHz processor. I'm curious as to whether it was an issue with the Quicksilver or if the iMac was built better.
Both processors are Altivec, load-store and fpu active with one being a 7450 and the other a 7455- if that makes any difference.
How much RAM memory do you have on each machine? What is the buss speed?
How much cash memory each processor have? Anything could be the reason. If I am not mistaken both machines are PowerPC? Right?
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Old 27th July 2011
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More plays into it than CPU speed...does the 800 MHz machine have more RAM? Faster disks? Different compilation settings? Different compiler versions? Different compilers? Different OS's?
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Old 27th July 2011
Ninguem Ninguem is offline
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http://www.everymac.com/systems/appl...g4_933_qs.html

Lists:
Quote:
System Bus Speed: 133 MHz Cache Bus Speed: 933 MHz* (Built-in)
Details: This system has a 256k "on chip" level 2 cache running at processor speed (933 MHz) and a 2 MB DDR SDRAM backside level 3 cache "with 3.7-GBps throughput"..
http://www.everymac.com/systems/appl...ac_800_fp.html

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Quote:
System Bus Speed: 100 MHz (8:1) Cache Bus Speed: 800 MHz (Built-in)
Details: N/A
The Quicksilver PowerMac G4 has 1.5G RAM, FreeBSD 9.0 and the iMac has 786M RAM also with FreeBSD 9.0.


A problem I have with the Quicksilver is one of the disks had trouble running/being recognized. There would be a click-whirling sound while the disk was being accessed. I removed it and placed it into a B&W. The same disk worked fine in the other machine.

rocket357, I'm not sure about the disk speed on either model. Checking ad0 for the iMac gives me Seagate ST360015A- .

I don't have the Quicksilver up right now; but, I can get those specs up later.

Last edited by Ninguem; 27th July 2011 at 08:21 PM.
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Old 25th August 2011
Ninguem Ninguem is offline
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Quote:
Originally Posted by http://www.osnews.com/story/3997/Analysis_x86_Vs_PPC/page3/
The idea that x86 have RISC-like cores is a myth. They use the same techniques but the cores of x86 CPUs require a great deal more hardware to deal with the complexities of the original instruction set and architecture.
I've wondered about this for reason that compiling and performance is nearly the same for processors within each architecture.
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