Quad-Core and Eight-Core Mac Pros (2009 editions)

Though you wouldn’t know by looking at it, Apple’s new tower, the Mac Pro, has just received a major overhaul. The two tower models pack a brand-new processor and video system, and feature a reorganized internal design. However, they have lower clock speeds than their predecessors.

Last year’s standard Mac Pro ( ) featured a 2.8GHz eight-core Intel Xeon processor based on the Harpertown/Penryn architecture. This year, there are two models: a quad-core system with a 2.66GHz Nehalem Xeon processor, and an eight-core model running two quad-core Xeon processors at 2.26GHz. Also new to the Mac Pros are Nvidia GeForce GT 120 graphics cards and a revamped interior designed to ease user access for upgrading internal components.

Similar but different

Aside from the second optical-drive slot on the front, the Mac Pro continues to use the same big-handled, aluminum case as the Power Mac G5, introduced nearly five years ago. There are some minor changes to the exterior, though—specifically in the type and number of connections. First, the two FireWire 400 connectors from previous generations have been replaced with backward-compatible FireWire 800 ports, bringing the number of FireWire ports to four—two on the front and two on the back. The five USB 2.0 ports, two on the front and three on the back, remain. On the graphics card, one of the two dual-link DVI connectors at the rear of the system has been replaced with a Mini DisplayPort connector, which lets you connect either to  Apple’s 24-inch LED Cinema Display ( ) or, with adapters (not included), to a second DVI display.

Upon opening the case, you immediately notice major changes in the layout of the components. The memory modules are no longer installed on two sliding trays—instead, the memory and processor all rest on a sled at the bottom of the case, which you remove by releasing two latches. The quad-core Mac Pro has four memory slots that ship with 3GB, 6GB, or 8GB of 1,066MHz DDR3 SDRAM modules; the eight-core Mac Pro has eight DIMM slots for a maximum of 32GB of RAM. The memory design no longer requires the large heat sinks.

The Mac Pro still has four internal cable-free hard-drive slots, using a sliding tray to attach the drives directly to the motherboard. Now, though, the large plastic piece holding the fan near the front of the Mac Pro is much smaller, giving your fingers more room to grip the hard-drive sleds. This is a small but welcome change. I can’t tell you how many times I’ve struggled over the years to remove that first drive. Another nice design change helps ease the removal of PCI cards from the four full-size PCI Express 2.0 card slots. In the past, to remove a card, you’d first need to turn two large thumbscrews that held a small plate keeping the cards in place. Then you had to feel around behind the card, searching for a little plastic tab mounted on the motherboard, which you needed to lift up in order to release the card. With the new Mac Pro, that second step is much easier. You now simply push a single thin bar that extends across all the PCI Express 2.0 slots to release any or all cards. Apple has also made installation of its add-on Apple RAID card much easier: you just put it into the clearly marked top slot, and you’re ready to go.

Installed in the first PCI Express 2.0 slot is the new Nvidia GeForce GT 120 graphics card with 512MB of video RAM; the last generation of Mac Pros came standard with an ATI Radeon HD 2600 XT graphics card with 256MB of memory.

2.66GHz Quad-Core/2.26GHz Eight-Core Mac Pro Speedmark Scores

New processor

The new Mac Pro uses Intel’s Xeon 3500 or 5500 quad-core processors, part of the new Nehalem family of microprocessors. Several major architectural innovations have the new processors featuring all four cores on a single die, making its 8MB of L3 cache available to any and all processing cores. The memory controller is now on-chip, giving the processor faster access to the main memory, and eliminating memory latency by up to 40 percent. 

Previously, the Mac Pro had 12MB of L2 cache per processor, with 6MB shared between pairs of processing cores. Each processor now has full access to 8MB of L3 as well as a small amount of dedicated L2 cache, whereas the previous Mac Pro had no L3 cache.

A technology called Hyper-Threading creates two virtual cores per each physical core, allowing each physical core to run two processes at once, which helps use the available processing power more efficiently. Also new to the Nehalem processors is a technology Intel calls Turbo Boost. Turbo Boost helps speed up the majority of applications that haven’t been written to take full advantage of multicore processors by allowing the system to spin down idle processing cores while increasing the speed of the processors in use. This lets a 2.93GHz Xeon, for example, run at speeds as high as 3.33GHz, Apple says.

Performance

So do all of these innovations translate to better performance? The 2.66GHz quad-core Mac Pro posted faster speeds in Photoshop, Compressor, iMovie, iTunes, and 3-D game benchmarks than the previous standard eight-core Mac Pro. That’s pretty impressive considering that the new Mac Pro is using only half the number of processing cores as last year’s standard configuration—and at a slower speed. The new quad-core’s score in our overall system performance suite, Speedmark 5, was 16 percent faster than that of the previous 2.8GHz eight-core Mac Pro. It was also 27 percent faster in our Photoshop tests, and 20 percent faster at Compressor than the older system.

The new 2.26GHz eight-core Mac Pro has twice as many processing cores as the 2.66GHz quad-core model, but each core runs 15 percent slower than the cores in that 2.66GHz quad-core Mac Pro. Because many applications have a difficult time using even four processors efficiently, the advantage of having eight was not apparent in most of the application tests that make up our Speedmark benchmark test suite. In fact, the new eight-core system posted a lower Speedmark score than the quad-core system, and bested it in just one test—Cinema 4D, where it posted a 28 percent faster time.

Pro app testing

We run Speedmark on all Mac systems, so the suite is light on the few industrial-strength professional applications that take full advantage of multicore processors. Speedmark tests are also run one at a time, which can mask the advantage of increased RAM. For those reasons, we decided to add a couple of tests to the suite to better test the Mac Pro, namely Mathematica ( ) and a ProRes Compressor test.

In these tests, the applications recognized and used all 16 virtual cores of the new eight-core Mac Pro. In MathematicaMark 7, the new quad-core Mac Pro received a score of 10.1, nearly identical to the 9.7 score of last year’s eight-core 2.8GHz Mac Pro. The new 2.26GHz Mac Pro scored 16.8, or 73 percent higher than last year’s eight-core Mac Pro. In our ProRes encode test to Compressor’s H.264 iPod/iPhone 640 by 480 preset, the new 2.66GHz Mac Pro took 9 minutes and 38 seconds to convert our 6 minute and 41 second clip, about 6.6 percent longer than the older eight-core 2.8GHz system did. The new 2.26GHz Mac Pro was about 8.9 percent faster than last year’s model. The new Mac Pro’s graphics performance showed much improvement when running 3-D games at high resolution. With the Nvidia GeForce GT 120 graphics, the new Mac Pros were able to push through 44 percent more frames per second than last year’s standard 2.8GHz eight-core Mac Pro when running Call of Duty 4 at 1,920 by 1,200 pixels, and nearly twice as many frames per second when running Quake 4 at high resolution. The new 3.06GHz 24-inch iMac ( ), with its Nvidia GeForce 130 graphics chip, beat both Mac Pros in our most of our graphics tests.

Macworld’s buying advice

The new Mac Pros, with their cutting-edge Nehalem processor technology, are able to execute more tasks at a faster clip, despite lower processor speeds. And their new internal design makes adding hard drives, memory cards, and PCI Express 2.0 cards easier than ever. Apple’s most expandable Mac is the pro platform for power users.

With its improved graphics, memory bandwidth, and reduced memory latency, the 2.66GHz quad-core Mac Pro was faster than the 2.8GHz eight-core Mac Pro, and at $2,499 costs $300 less. It would be a fine purchase for anyone replacing an older Mac or buying a new one for the first time. That is especially true for people who work with processorintensive apps such as video or graphics.

It’s harder to recommend that people spend $800 more for the new $3,299 2.26GHz eight-core Mac Pro if they don’t run software written for the top-of-the-line Mac Pro’s eight processor cores. Though the 2.26GHz model was faster at most individual tasks than the previous eightcore 2.8GHz Mac Pro, and very fast in a few of our professional applications tests, it was slower than the new quad-core model at the majority of our application tests.

[James Galbraith is Macworld’s lab director.]