Apple's New Dual 2.5 GHz Power Mac G5--How Fast Is It?--Part I.

Our new dual 2.5 GHz Power Mac G5 (D2.5) showed up last week. Supplies of the latest "Fastest Mac on the Planet" have been severely constrained and still show a 3-5 week time to ship after ordering on the online Apple Store. The new D2.5 replaces our dual 2.0 GHz Power Mac which previously held that title. The press of other business kept us from setting it up and running it through its paces until this past weekend but we were able to spend enough time to bring you this first part of our report.

Aside from the obvious 25 per cent increase in CPU power, the new King of the Hill has a brand new liquid cooling system, 8x vs 4x SuperDrive, USB 2.0 ports and a RAM bump in the ATI graphics card. The new graphics card is an ATI Radeon 9600 XT with 128 MB of video ram on the card, up from and ATI 9600 Pro with 64 MB in the dual 2. All we have done to our D2.5 so far is to add 1 GB of PC 3200 (400MHz) RAM for a total of 1.5 GB. However, we have an Nvidia 6800 graphics card on order along with one of Apple's incredible 30" Cinema Displays which will replace our 23" Cinema, probably near the end of October.

So how fast is it? Using a test file with Adobe Photoshop 8.0 (CS) Apple claims that the D2.5 is nearly twice as fast as a Dell 3.4 GHz Wintel and some 72 per cent faster (see Apple's chart at right). Apple's chart also indicates that the D2.5 is some 9 percent faster than the D2.0. To findout for ourselves, we ran part of our complete suite of speed tests on a fully updated Mac OS X 10.3.5.

The complete test suite consists of a number of "canned" benchmarks and several so-called "real world" tests. They are described in detail in our G4 Cube 1.2-GHz upgrade review and are simple enough for anyone to repeat on their own Mac for comparison. For Part 1 of our report we have included only the benchmarks. In Part 2, after we have used the D2.5 for awhile, we will include the "real word" tests.

The results from our new D2.5 are shown in the table below along with those from our dual 2-GHz Power Mac G5, also stock except for 1.5-GB RAM. Each test was run three times with a reboot in between and the average score or number of seconds computed.

The D 2.5's CPU is 25 per cent faster than the D2.0's and this is reflected in the Altivec Fractal and Xbench CPU tests. But based on the other benchmarks, the new D2.5 is for the most part some 15-22 percent faster at tasks than our former champ. This is generally better than Apple's chart above. The G5s performance seems to scale a little bit better to clock speed than did the G4s.

We have a couple of salient observations made during the short time using our new D2.5. The D2.5 runs hotter at the heatsink, some 172 dF versus 140 dF, than our D2.0 model according to ThermographX. It is also noticeably noisier but not appreciably so most of the time. The fans are activated and they run faster (louder) when the CPU is set to "Highest" performance in the Energy Saver preference pane. When a CPU intensive task is runing the fans rev up quickly and then rev down just as quickly when the task is completed--these adjustments are much quicker than our D2.0 accomplished.

In summary, the new Dual 2.5 GHz Power Mac G5 measures and actually "feels" faster than the former champ, just as expected. Those with a real need for speed will find this new Power Mac from Apple just right for them. And the new liquid cooling system is just plain cool, no pun intended.