AnandTech: Apple new Power Mac G5’s biggest improvement is the move to PCI Express

“All of Apple’s new Power Mac G5s feature dual-core processors, but what it allows Apple to do is outfit the lower end Power Mac G5s with only a single processor and still offer the same number of concurrently executable threads as the older dual processor G5s. Granted you do lose some performance because the two cores now must share a single FSB, whereas the older dual processor machines had an independent FSB per processor. But any performance loss you’d see there is more than made up by the fact that each core now gets a full 1MB L2 cache,” Anand Lal Shimpi writes in his AnandTech Weblog.

“Apple does give up a bit of clock speed at the high end by moving to dual core, with the fastest G5 now topping out at 2.5GHz vs. 2.7GHz. The larger L2 cache will make up for some of that difference, but not all. Obviously the high end G5 now offers more than just a faster clock speed, it now features two dual-core CPUs. But, just like we’ve seen in the PC world, those applications that exhibit a high level of TLP will appreciate the dual dual-core CPU configuration, while others may actually run faster on the older dual 2.7GHz setup. For the most part, most OS X applications seem to be highly threaded in nature, and my money is on a dual dual-core configuration being the more desirable one,” Lal Shimpi writes.

“With the new G5s Apple has moved to DDR2-533, offering a total of 8.5GB/s of memory bandwidth. Unlike Intel’s DDR2 platforms however, the G5s can actually use the added memory bandwidth… The move to dual-core is interesting, but given that the previous line of G5s were all dual processor to begin with, it’s not a huge improvement. In my opinion, the biggest improvement to the new G5s is the move to PCI Express. And here’s one thing I really do like about Apple, when they move to a new technology, they really move to it,” Lal Shimpi writes. “There isn’t a single parallel PCI slot in the new G5s, instead you’ve got one x16 slot, two x4 slots and one x8 slot. The other interesting thing is that all of the PCI Express slots use a x16 connector, so although there is only one x16 slot (electrically), all four slots can fit a x16 card. Apple uses this support to their marketing advantage, by mentioning that the new G5s can support up to 8 displays through 4 dual-display PCIe graphics cards… he dependency of OS X on high speed CPU/graphics communication means that the move to PCI Express graphics was a must, and I am pleased with the way in which Apple made that move.”

Full article here.

Advertisement: Order the new Power Mac G5 from the Apple Store now. Dual-core PowerPC processors, a modern PCI Express architecture, and wicked-fast workstation graphics. From $1999. Free shipping.

Related MacDailyNews articles:
Photos of new dual core Apple Power Mac G5 interior, ports, and more – October 19, 2005
Analyst: new Power Mac G5 and PowerBook models should help Apple – October 19, 2005
First benchmark tests of Apple’s new Power Mac G5 dual-core machines – October 19, 2005
Apple introduces Power Mac G5 Quad and Power Mac G5 Dual – October 19, 2005


  1. > “Over my head!”

    And that’s probably part of the reason why you use a Mac in the first place … this stuff isn’t of interest to you, or is simply too much information.

    > “Yeah, but can I play high-end video games on it?!”

    No. You have been a bad boy. Go to your room and play with your X-Box.

  2. i just have a powerbook with it’s display and another display. eight displays would be like heaven!
    by the way, is there a way to get more than one extra display hooked up to my powerbook? a video card or anything…

  3. Anon , if he wanted to play a decent game he’d use his ps-2 , not that pos .

    As for more information equalling quality , some of the finest works of literature , art and music have been the briefest .

  4. Most Mac users can’t understand this technical writeup. That’s why they buy into Apple: They’re content to believe that they’re told – “Mac is better then anything else.” But they have no idea why it is or how to question if it isn’t. Simpletons is what they are. Just Lemmings that like the pretty things…

  5. New Dual cores are liquid cooled and the single dual cores have 4 cooling pipes when they only need 2, suggesting single dual core PowerMacs will have a short life like the single processor PowerMac G5’s did. So buy a Quad.

    The Dual cores are less in performance than two processors, the quad is not 4 x in performance, so watch out for that. Sharing the FSB is killing the performance, so expect faster FSB’s over time to increase performance and create new sales.

    Apple is keeping the performance down to keep the heat down and induce a faster upgrade cycle. It might be possible to mod the new Quad with a better cooling system and increase the performance like PC’s overclockers do.

    30″ display is plenty enough, having more than one display is a pain as your moving your head around too much. With a 30″ you sit back and take it all in instead of scooting within a few inches like a 17″ CRT.

    With 4 30″ displays you have to sit back across the room to be able to take it all in, but it is very awesome to see it. Just unpractical with the bars in the way. Go with a projector instead if your going this route.

  6. This new computer called a Macintosh comes with a pointing device called a “mouse” and operating system called a “Graphical User Interface”

    There is no evidence any computer user wants to use these things


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