“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.
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