PRE-TEST BRIEFING:
New Dual-Core
and Quad-Core G5/2.5 Power Macs

NOTE: Since we posted this briefing, we've been able to assemble some CPU performance test results and 3D Game test results for the Quad-Core.

We've done some research while waiting to test the new Dual-Core and Quad-Core G5 Power Macs Apple introduced recently. Here's what we've gathered so far...

"What kind of memory should I get, ECC or non-ECC?"
There's a helpful article on the Apple site that explains what ECC memory does. It discusses how the Xserve with ECC memory uses Server Monitor to collect stats on the number of errors made by each memory module. ECC memory can handle one bit errors without crashing the app or system. But with multiple bit errors and "kaboom" -- no matter what kind of memory you have.

ECC memory will NOT make your G5 go faster -- or slower.

"Should I get more expensive, higher speed memory with lower latency?"
Apple ships the Power Macs with CAS 4 PC2-4200 memory. We tried the lower latency CAS 3 memory. None of our benchmarks ran any faster.

Apple says, in addition to moving from DDR 400MHz memory to DDR2 533MHz, the memory controller has been made for efficient than the previous model of G5 Power Mac, increasing the throughput to 8.5GB/s versus 6.4GB/s.

"Apple lists the nVidia GeForce 7800 GT as a CTO option on the Power Mac Specs and Graphics page but it's not on the Online Store drop down ordering menu." That was fixed on October 26th, 2005. You can now order the GeForce 7800 GT with your new G5 Power Mac for as little as $350 extra!

I believe the 7800 GT will end up being the most popular graphics card option since it provides the most bang for the buck. Apple's own Power Mac Graphics page shows it to be only slightly slower than the much more expensive Quadro FX 4500.

I did some testing on Quadro FX 3400 cards and GeForce 6800 Ultra PCIe cards on a Windows PC a few months ago. The GeForce was quicker running 3D games (Halo and Doom 3) and benchmarks that were pixel intensive (3DMark, OpenMark). The Quadro excelled at polygon intensive benchmarks (specVIEWperf).

One of our readers (Mark Wilkins) reminded us that the Quadro FX 4500 has additional features that are not present on either GeForce card. These include hardware support for anti-aliased points and lines, accelerated clip planes, and two-sided lighting -- features important to advanced design and visualization applications. It also has an integrated stereo 3D port. For those users who are considering the purchase to run software like Maya (which only supports hardware rendering on the Quadro cards), the Quadro may well be worth the extra money.

Some may choose the Quadro since it supports dual 30" Cinema displays -- the only currently shipping PCIe card that does. It also has 512MB of DDR3 memory. But if you are choosing the Quadro just to support dual 30" Cinemas, but don't need the advanced features, read the "Brainstorm" in the box below.

BRAINSTORM: Rob Reuss emailed me an interesting idea. Why pay $1650 for the Quadro FX 4500 graphics card in your new G5 Power Mac just in order to drive two 30" Cinemas? The GeForce 6600 and 7800 GT each support a single 30" Cinema. You have spare PCI Express slots. Why not get two cards? Put the GeForce 7800 GT in the 16 lane PCIe slot and the GeForce 6600 in the 8 lane PCIe slot. Make the display on the 7800 GT the primary. That way, when you run a demanding 3D app that takes over the screen, it will be running off the faster card in the fastest slot. This alternate scenario doesn't use more slots because the Quadro FX 4500 uses up two slots with it's "fat" heatsink. But here's the kicker: The cost of getting the GeForce 7800 GT is $350 if added initially as CTO option. The 6600 is available as a kit for $200. So for one-third the price of the single Quadro FX 4500, you have dual 30" Cinema support and a total of 512MB video memory.

"Why isn't Apple supporting SLI mode with adjacent 16 lane PCI Express slots?"
That scenario was part of my daydream, but when I ran tests on a dual-core AMD machine in SLI mode, it produced only a 21% gain in Doom 3 and a 20% gain in Halo. Plus not all apps are not SLI aware. Those findings might explain why Apple wasn't too concerned about offering SLI mode.

For those of you who aren't familiar with the term, "SLI" stands for "Scalable Link Interface" where special edge connectors on the top of PCI Express graphics cards enable you to link adjacent cards using a special jumper, thereby providing scalability and increased performance.

"I heard that any PCI Express graphics card will work in the new G5 Power Mac -- not just those sold by Apple. Is this true?"
It would be great if this were true.

If you go to the specifications page for the GeForce 7800 GTX on the nVidia site, it does list Mac OS X as a Supported OS (bottom right). But if you go to the drivers page, it only lists Windows drivers. In other words, when they say Mac OS X is supported, that means "by Apple only with proprietary drivers and firmware."

ATI has one "PC and Mac" compatible card (Radeon 9600 Pro 4X). They said it was tricky putting firmware for both platforms in the card. Requires a big ROM and careful programming. Supporting multiple platforms is not a slot issue (PCIe vs AGP) but a firmware issue as we see it.

"All PCI Express slots? What do I do with all my PCI-X and PCI cards? And when is someone coming out with PCI Express versions of SATA II?"
I'm getting a lot of email from frustrated would-be Dual-Core and Quad-Core G5 Power Mac owners like the one quoted above.