New 64-bit CPUs faster, but stuck in the 32-bit slow lane

Microprocessors that handle data in 64-bit rather than 32-bit chunks are billed as the next big leap for personal computers — a development so tremendous that it will re-ignite the industry’s sales, boost profits and open new, exciting markets.

Apple Computer Inc. has upgraded its top Macintosh computers with the PowerPC G5, and Advanced Micro Devices Inc. has launched the Athlon 64. Both 64-bit machines also run the software of today’s 32-bit world — a necessity given the scarcity of 64-bit programs.

I tested both systems and found good, sometimes spectacular, performance boosts. Both shaved minutes off computing-intensive tasks such as making DVD movies or ripping music.

The performance does come at a price — about $3,000 for the top-of-the-line Power Mac G5 and about the same for a system based on AMD’s flagship Athlon 64 FX-51.

And it’s safe to say all the improvements I noticed had little or nothing to do with the much-hyped 64-bit technology. That’s because software like Windows XP doesn’t support it yet. Apple’s a bit further ahead, but the programs I used were not optimized.

So what’s the big deal about bits? A 32-bit processor can handle up to 4 billion bytes of memory — an amount rarely approached in ordinary desktop computing today. By comparison, a 64-bit chip can address 18 billion billion bytes.

That’s great for massive database applications, nuclear blast simulations or long-range climate predictions. Down the road, 64-bit desktop processing will help PCs render images with lifelike realism, AMD officials say.

But that’s the future — when there’s software available, and when so much memory will be affordable. Today, both the Athlon 64 and Apple’s G5 are stuck in a 32-bit world.

Even so, both machines are impressive. Processor speeds are bumped up from previous generations. Various data freeways between the processor and memory, as well as other subsystems, have been widened. Such bottleneck-busting moves improve overall performance.

I tested a system based on the highest end of the Athlon 64, the FX-51. The $733 processor runs at 2.2 gigahertz. AMD built the computer to show off the new processor. Retailers such as Alienware Corp. are already shipping similar computers for about $3,000.

Booting into the 32-bit version of Windows XP Professional was quick, and the system was stable while using the Web, e-mail, games and a word processor.

I launched the latest version of Windows Media Player and converted a 55-minute CD into Windows Media Audio (WMA) format. It blazed through that task in only 2 minutes, 20 seconds. My fairly recent 2.8 gigahertz Pentium 4, by comparison, took 4 minutes, 10 seconds.

It looked like the Athlon 64 blew away Intel Corp.’s Pentium 4.

Not so fast.

After pondering the results, I realized the music was ripped from different drives. After I moved the drive from my Pentium system to the Athlon, it ripped and encoded the WMA files in 4 minutes, 51 seconds.

In another test, I taped 30 minutes of the family cat doing cat things. I imported it into both systems and created a DVD using ArcSoft’s ShowBiz 2 software.

The Athlon pulled ahead in this test, though it benefited from twice as much physical memory as my Pentium 4 system and from speedier hard drives. The Athlon took 21 minutes; the Pentium 30 minutes.

Apple, meanwhile, is selling the Power Mac G5 ($2,999) with a version of Mac OS X that can take advantage of the hardware, including a 32-bit-busting 8 gigabytes of memory. (But my test system came with 2 gigabytes; the model usually ships with 512 megabytes.)

My review unit ran on two, 2 gigahertz G5 processors built by IBM Corp. I compared the results to my old system, which has two 800-megahertz processors from Motorola Inc.

I ripped my 55-minute music CD, converting it into the Advanced Audio Coding format. It took 3 minutes, 56 seconds on the G5 system with Apple’s iTunes 4. The G4, with only 256 megabytes of memory, didn’t fare so well: It took just over 8 minutes.