Apple's Mac Pro: A Discussion of Specifications

GPU Options

We had hoped for more extensive GPU options with the Mac Pro, unfortunately Apple only gave us three. The options are now a GeForce 7300 GT for those who aren't doing any real 3D work, an ATI Radeon X1900 XT and a NVIDIA Quadro FX 4500.

The Radeon X1900 XT used in the Mac Pro appears to have a 1.3GHz memory clock, which is slower than the 1.45GHz clock of the PC version. The core clock is also slower than the PC version at 600MHz, instead of 625MHz. Historically, ATI Mac Edition cards have always been clocked lower than their PC counterparts; ATI explained the reasoning behind this disparity as having to do with basic supply and demand. The demand for Mac video cards is lower than their PC counterparts, so ATI runs them at lower clock speeds to maintain their desired profit per card regardless of whether they are selling to Mac or PC markets.

The interesting offering on the Mac Pro is the Quadro FX 4500, which is basically a higher clocked version of the GeForce 7800 GTX with some additional workstation class features. With a 450MHz core clock (compared to 430MHz on the 7800 GTX) and a 1050MHz memory clock, the Quadro FX 4500 should actually be slower than the Radeon X1900 XT on the Mac Pro. If you compare the X1900 XT to NVIDIA's offerings on the PC, you generally need a 7800 GTX 512MB (with its faster clock speeds) or a 7900 GTX to outperform the X1900 XT, a vanilla 7800 GTX won't cut it. However, Apple's own benchmarks indicate that the Quadro FX 4500 is faster in games than the Radeon X1900 XT; even though Doom 3 and Quake 4 are the titles of choice, ATI should still be faster. It's tough to say which will run cooler/quieter, the X1900 XT is built on a 90nm process while the Quadro FX 4500 was a 110nm GPU, but with different clocks, transistor counts and fans we'll just have to find out for ourselves.

We're working on getting both cards in house for a head to head comparison, but there could be some explanations for the performance standings being what they are today. NVIDIA's OpenGL drivers may be better than ATI's under OS X or it's also possible that some of the GPU-level enhancements enabled on Quadro GPUs are somehow coming into play in the Quake 4/Doom 3 benchmarks that Apple is reporting.

Finally there's the default configuration option, the NVIDIA GeForce 7300 GT. If you plan on doing any GPU based rendering, then the 7300 GT is more than enough for OS X, especially since it comes equipped with 256MB of memory. Even 30" Cinema Display owners will have a fairly smooth Exposé experience with 256MB of video memory.