The Test

We tested a total of five configurations throughout all of our tests: a dual socket (single core) PowerMac G5 2.0GHz, a dual socket (single core) PowerMac G5 2.5GHz, a dual socket (dual core) Mac Pro 2.0GHz and a dual socket (dual core) Mac Pro 2.66GHz.  The fifth configuration was the dual socket dual core Mac Pro 2.0GHz with one socket disabled, thus running as a dual core Mac Pro 2.0GHz.  The reason for this fifth configuration is to help point out the areas where the Mac Pro is doing better than the PowerMac G5 simply due to its four cores (vs. two in the G5) and where the advantage is purely architectural. 

We kept configurations as close as possible, each system featured 2GB of memory (the Mac Pros used 4 x 512MB FB-DIMMs in order to run in quad channel mode) and used the same Seagate 7200.9 250GB HDD. 

Video cards could not be kept controlled since the PowerMac G5 systems used AGP cards while the Mac Pros used PCIe cards; for this reason we did not run any GPU bound tests and thus there should be no tangible difference in performance due to the differing graphics cards.  The G5s used a 256MB ATI Radeon 9600 Pro while the Mac Pros used a 256MB GeForce 7300 GT.

All systems used the latest updates to the OS and all software as of the time of publication.

Using the Mac Pro Memory Performance
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  • tmohajir - Thursday, August 17, 2006 - link

    I had the same question. I was debating whether to by 2 x 512MB or 1GB, and then thought it might affect performance if I went with the 1GB sticks. I think for now the best bet would be to buy 2 512s so that each branch has a channel with the same amount of memory. Then if I want to upgrade later, move all 4 512s to riser 1, and buy 2 1GB dimms when the price drops a little more and stick them in riser 2. So that way you still have 2GB total per branch.
  • dborod - Thursday, August 17, 2006 - link

    I decided to order my MacPro with 4 x 512 MB dimms so as to be able to fully utilize the available memory bandwidth. It seemed the easiest and safest approach for now.
  • dborod - Thursday, August 17, 2006 - link

    I decided to order my MacPro with 4 x 512 MB dimms so as to be able to fully utilize the available memory bandwidth. It seemed the easiest and sa
  • Questar - Wednesday, August 16, 2006 - link

    Why use MP3 encoding for performace testing in a multi cpu environment? MP3 encoding is not very threadable, and most likely is not threaded to any great extent in iTunes.
  • Griswold - Thursday, August 17, 2006 - link

    Somebody obviously has never used the multithreaded encoder of the LAME MT project. I see gains of up to 50% with that. Sure, that may not be relevant for a mac pro user, but it is proof that MP3 encoding benefits from SMT.
  • Questar - Thursday, August 17, 2006 - link

    Griswald stikes again.

    Yes I've heard of LAMEMT. So how's that sound quality you're getting without a bit resevoir? Pretty crappy I'll bet.
  • Griswold - Friday, August 18, 2006 - link

    Oh give me a break nutsack. Dont pretend you know what you're talking about here, as it doesnt match your first (false) post - you obviously never used LameMT. Disabling bit reservoir may come with a certain loss of quality, but its not nearly as much as you (or the poster above) want it to make to be. I'm willing to bet 95% of the people using mp3 wont notice the difference.

    I'm listening to the same song encoded with standard Lame and LameMT and the quality is virtually the same. Of course, you'll now say your ears are so much better, you got so much better audio equipment and what not.. but meh, it's just questdork talking.
  • michael2k - Saturday, August 19, 2006 - link

    The same 95% of the population who purchase tracks from the iTMS I bet :)
  • Questar - Friday, August 18, 2006 - link

    Thanks for the best laugh I've had all week!
    I really needed it!!
  • saratoga - Thursday, August 17, 2006 - link

    quote:

    Somebody obviously has never used the multithreaded encoder of the LAME MT project. I see gains of up to 50% with that.


    Yeah but you also lose quality, so very few people use it.

    quote:

    Sure, that may not be relevant for a mac pro user, but it is proof that MP3 encoding benefits from SMT.


    Not exactly. LAMEMT is only multithreaded when you use parts of the MP3 standard that can be multithreaded. Typical MP3 encoding as done by lame, itunes, xing, etc simply can not be multithreaded. LAMEMT can be multithreaded because it disables certain features that are incompatable and then implements software pipelining.

    The LAME devs have talked about trying to work around this problem in the past, but so far most people seem to think its just not worth the effort because the speed up is much worse then just running two copies of LAME (which gives a 100% speedup verses the 50% you saw), and of course the unresolved questions about just how badly quality would be hurt by rewriting LAME profiles from scratch to use the approach in LAMEMT.

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