64-Bit Takes Off

AMD's chip supports 64-bit computing, ushering in a new era for desktops. But the best reason to buy the CPU is strong performance on familiar 32-bit apps.

64-bit desktop computing has taken a significant step toward becoming a pervasive reality: AMD's release of its Athlon 64 chips--and Apple's launch of its G5 CPUs--means 64-bit processors, once reserved for servers and high-end workstations, are now in PCs available on retail shelves.

In time, 64-bit PCs could change the face of desktop computing. A 64-bit chip can run longer, more complex instructions than a 32-bit one, improving performance of data-intensive tasks such as audio and video encoding, advanced engineering design apps, and, naturally, games.

Equally key is a 64-bit CPU's ability to recognize and use a lot more RAM. Today's 32-bit chips, such as AMD's Athlon XP and Intel's Pentium 4, can address up to 4GB of RAM split between the OS and applications. Few PCs have that much memory, and even fewer apps use it. But with ever-more-complex software, that limitation may become a bottleneck, making Athlon 64's ability to address a whopping terabyte (1000GB) of physical memory very attractive.

But you will need a 64-bit-capable operating system, new hardware drivers, and 64-bit applications to fully take advantage of such a chip, and therein lies the rub.

A few Linux distributions, including Red Hat and SuSE, already offer (or will soon) 64-bit editions for Athlon 64s, but Microsoft's 64-bit Windows XP for these chips won't ship until early 2004--and even it won't offer most users what they really need (see "Sneak Peek"). Aside from a handful of expected programs, such as DivXNetworks' DivX video encoder, 64-bit desktop software will be an even longer wait. The lack of full support is one reason Intel has no current plans to introduce a 64-bit desktop chip (see "Why 64-Bit Now?" for more on Intel's views).

AMD knew 64-bit desktop computing wouldn't be ready for prime time right away, so it made its 64-bit Athlons hybrid CPUs that can also run today's 32-bit apps. And our initial tests show the chips run them very well (see the chart).

Apple's latest OS X has 64-bit extensions, providing the new Mac G5s and a few optimized apps a taste of greater power. But that isn't quite enough to give Apple a wholesale performance edge. (For more on Apple's 64-bit platform, and its G5's performance versus Athlon 64 PCs, see "64-Bit Computing According to Apple.")

The Score

We tested three systems using the high-end 2.2-GHz Athlon 64 FX-51 chip with dual-channel memory, and a PC with the more mainstream Athlon 64 3200+, which runs at 2 GHz and has single-channel memory. We also looked at an identically configured 3.2-GHz P4 PC for comparison. All PCs had 1GB of DDR400 memory and an ATI Radeon 9800 Pro graphics card. All tests were performed with 32-bit software.

The three Athlon 64 FX-51-based units--from Alienware ($3535), Falcon Northwest ($3245), and Voodoo ($3250)--notched an average PC WorldBench 4 score of 142, the fastest we've seen. ABS' Athlon 64 3200+ PC ($1924) scored 139; Alienware's P4 comparison unit ($3143) earned 126. The scores for three previously tested 32-bit Athlon XP 3200+ PCs averaged 136; seven previously tested 3.2-GHz P4 units earned an average of 127. (Prices above exclude a monitor and speakers.)

Systems with the FX-51 showed pronounced improvements in some of our more CPU-intensive tests, particularly AutoCAD, where they were about 44 percent faster, on average, than the P4 unit. The FX-51 PCs also stood out on our Premiere tests, and posted top scores on the Photoshop and VideoWave tests. The P4-based PC had the best score in our Musicmatch test.

In our game tests, again the FX-51 PCs were clear winners, posting noticeably higher scores. (Note: Lower resolutions show CPU power better than higher ones because the graphics subsystem contributes more at high res.)

Memory Boost

Besides adding 64-bit capabilities, AMD made other improvements to its new CPUs. They include a 1MB L2 cache (up from 512KB), a faster system bus based on HyperTransport technology (up to 1600 MHz), and new SSE 2 instructions. But probably the most important change was the move to an on-chip memory controller.

Typically the memory controller resides on the motherboard as part of the chip set, connected to the CPU via the frontside bus. Athlon XP has a maximum frontside bus speed of 400 MHz; Intel's latest P4s offer 800 MHz. By integrating the memory controller, AMD gives memory a private channel to the CPU: It no longer has to share a pipe with other components and needs no middleman to process its request. Unlike CPU cache, the integrated memory controller runs at the memory speed, not CPU speed.

"The on-board memory controller provides more bandwidth and drops the latency," says Kevin Krewell, general manager at research firm MicroDesign Resources. Lower latency means less time between the CPU asking for data from RAM and getting it.

Two Athlons

AMD's new chips also have real architectural differences between them. For example, the FX-51's dual channels can move up to 6.4GB of data per second with DDR400 while the mainstream Athlon 64's single-channel DDR can move up to 3.2 GBps. More: The FX-51 requires a 940-pin socket (the Athlon 64 3200+ uses the new Socket 754), and more expensive registered-memory DIMMs. Usually reserved for servers, a registered DIMM includes an internal buffer that allows more memory chips per DIMM, but with a delay of half a clock cycle required to help prevent errors. The FX-51 is also easier to overclock than the Athlon 64, although AMD won't officially recommend doing that (it still voids the warranty).

AMD charges vendors $733 for each FX-51 in lots of 1000, versus $417 for the Athlon 64 3200+. (The 3.2-GHz P4 is $637.) That's a hearty premium for the FX-51, but it's a price that performance buffs are likely to pay, says Dean McCarron, principal analyst with Mercury Research.

There should be little confusion between AMD's two new chips, but you'll note the company gave the 2-GHz Athlon 64 the same 3200+ performance rating as that of its last 32-bit Athlon XP chip (FX-designated chips dropped the performance ratings altogether). Check before you buy: AMD will sell both 3200+ CPUs for the near future.

Why 64-Bit Now?

So if Athlon 64s perform so well at 32-bit tasks, why is AMD pushing the 64-bit angle at all? Because company executives believe the 64-bit desktop age is dawning now.

Once video editors watch a 64-bit PC encode video directly to a DVD on the fly, they'll want one, says Rich Heye, vice president of AMD's microprocessor unit. And once gamers see the cinematic quality that 64-bit chips help make possible, they'll want one. Though mass-market adoption will take a few years, "the average lifetime of a PC is three to four years, and I think a lot of people will be running 64 bits before that's up," Heye says.

Executives at Intel disagree, seeing 64-bit computing as largely a server technology in the short term. "With just 5 percent of servers using 64-bit addressability, there is little need today [for 64 bits] on the desktop," says George Alfs, Intel spokesperson, adding that without software and other tools to make it work at its best, 64 bits doesn't mean much.

MDR's Krewell sees Intel's resistance to 64 bits for the desktop as a move to protect its sizeable investment in its 64-bit Itanium CPU, designed for servers and workstations.

Should AMD's 64-bit initiative take off, Krewell says he's convinced Intel has a backup plan. "There is no technical reason they cannot implement a 64-bit extension in their desktop chips," he says.

Intel's Alfs says the company will continue to focus on "bringing benefits that PC users can use now." To that end, at press time the company announced a new chip, the 3.2-GHz P4 with Hyperthreading Technology, Extreme Edition, aimed at gamers who want top performance. This 32-bit chip boasts 2MB of L3 cache and should be shipping shortly after you read this. (The chip was unavailable in time for testing for this story. See our separate news article for performance results.) Intel's next-generation chip, code-named Prescott, will also debut before year's end. Prescott's boosts include a larger L2 cache, new instructions, and improved hyperthreading technology.

Meanwhile, with Athlon 64, AMD has reignited the chip wars. That's always good news for users, says MDR's Krewell.

Power users are well served by Athlon 64 FX PCs, which are currently atop the performance heap--with prices to match. If you don't need to squeeze every last bit of power from your PC, a unit with the Athlon 64 3200+ or Intel's 3.2-GHz P4 may be your best bet--though systems with the former are likely to save you some money over P4 PCs.

The Bit Map

Mark MatchoFifteen years passed between the first 32-bit chip and a full 32-bit Windows. The 64-bit switch may be faster: Both chips and OS are here.

64-Bit Era

Sept. 2003: Athlon 64 3200+ (2 GHz), Athlon 64 FX-51 (2.2 GHz) Sept. 2003: Windows XP 64-Bit Edition for Athlon 64 beta April 2003: AMD Opteron 240, 242, 244 July 2002: Itanium 2 (900 MHz, 1 GHz) Oct. 2001: Windows XP 64-Bit Edition for Itanium May 2001: Intel Itanium (733, 800 MHz)

32-Bit Era (Ongoing)

Oct. 2001: Windows XP Oct. 2001: Athlon XP 1500+ (1.33 GHz) Nov. 2000: Pentium 4 (1.4, 1.5 GHz) Feb. 2000: Windows 20001 Sept. 1999: AMD Athlon (600 MHz) Feb. 1999: Pentium III (450, 500 MHz) May 1997: Pentium II (233 MHz) March 1993: Pentium (60, 66 MHz) April 1989: 486DX (25 MHz) Oct. 1985: Intel 386DX (16 MHz)

16-Bit Era (Ongoing)

June 1998: Windows 981 Aug. 1995: Windows 951 April 1992: Windows 3.1 May 1990: Windows 3.0 Nov. 1985: Microsoft Windows 1.0 Feb. 1982: Intel 80286 (6 MHz)

1Has 32-bit extensions.

Test Report (chart)

64-Bit Athlon PCs Shine on Graphics Apps...

The new 64-bit Athlon FX PCs did particularly well on AutoCAD, Premiere, and Unreal Tournament (all 32-bit applications).

System	Processor	PC WorldBench 4 score	Time (in seconds) required to run test. Lower is better
			AutoCAD	Musicmatch 7.1	Premiere 6	Photoshop 7.0.1	VideoWave 1.5 (DivX)
Alienware Aurora	2.2-GHz Athlon 64 FX-51	141	171	153	174	257	78
Falcon Northwest Mach V	2.2-GHz Athlon 64 FX-51	142	169	150	181	256	68
Voodoo Fury	2.2-GHz Athlon 64 FX-51	143	174	153	168	253	78
ABS Awesome 5100	2-GHz Athlon 64 3200+	139	189	165	197	271	72
Alienware Area 51	3.2-GHz Pentium 4	126	246	140	217	269	82

...And They Got Game, Too

System	Processor	Return to Castle Wolfenstein (in frames per second)				Unreal Tournament 2003 (in frames per second)
		1024 by 768 resolution, 16-bit	1024 by 768 resolution, 32-bit	1280 by 1024 resolution, 32-bit	1600 by 1200 resolution, 32-bit	1024 by 768 resolution, 16-bit	1024 by 768 resolution, 32-bit	1280 by 1024 resolution, 32-bit	1600 by 1200 resolution, 32-bit
Alienware Aurora	2.2-GHz Athlon 64 FX-51	145	136	131	108	378	263	173	124
Falcon Northwest Mach V	2.2-GHz Athlon 64 FX-51	147	139	133	112	382	281	187	134
Voodoo Fury	2.2-GHz Athlon 64 FX-51	144	138	132	112	377	285	188	134
ABS Awesome 5100	2-GHz Athlon 64 3200	100	96	95	90	340	269	182	131
Alienware Area 51	3.2-GHz Pentium 4	133	127	121	105	292	243	173	124
How We Test: All PCs had 1GB of RAM. The ABS PC had an ATI Radeon 9800 Pro graphics card with 128MB of RAM; all others used the same card with 256MB. All units ran Windows XP Home except the Alienware Aurora, which ran Windows XP Professional. All systems included RAID-striped 7200-rpm hard drives, except the Voodoo, which had 10,000-rpm drives. All PCs tested with PC WorldBench 4, PC World's application-based benchmark. In AutoCAD we time AutoDesk Group International's AUGI Gauge 15 tests, which run CAD tasks. In Musicmatch Jukebox 7.1 we time the conversion of six.wav files into 160-kbps.mp3 files, then resample the files to 64 kbps. In Adobe Premiere 6 we time the preview rendering of two video tracks and one audio track, export the finished movie to various video formats, and verify the encoding. In Photoshop 7.0.1 we rotate a JPEG file, save it as a thumbnail and EPS file, and apply a variety of filters, timing the whole process. In VideoWave 1.5 we time the process of taking a raw AVI video file, adding effects, and converting it into an MPEG-2 file using the DivX codec. In Return to Castle Wolfenstein, we measure frame rates during a recorded demo; the Unreal Tournament 2003 test measures frame rates during a fly-through of one game level. Tests developed and conducted by the PC World Test Center. All rights reserved. Chart Notes: On PC WorldBench 4 and games, higher is better; elsewhere, lower is better. Best scores in bold.

Sneak Peek: Windows XP 64-Bit Edition

Although the first 64-bit Athlon PCs will ship with a standard Windows XP (a 32-bit operating system), a version of the OS that can fully harness the new chip's power is on its way: Windows XP 64-Bit Edition is in beta testing, and Microsoft expects to ship the OS in the first quarter of 2004.

(Note: Although the new OS bears the same name as the 64-bit version of Windows for Intel's Itanium platform, the two OSs are not interchangeable and do not have the same features.)

But upgrading to XP 64 could mean giving up functionality without getting much in return. In fact, XP 64 looks like a throwback to Windows past: Its interface mirrors that of Windows 2000 or even Win 98. Microsoft has not disclosed what else will be in the OS, so it is possible that you'll still get most of XP's other features.

XP 64 won't have the 32-bit XP's support for DOS apps at all, nor will it run 16-bit apps (but it should have no trouble with 32-bit software). More important, 64-bit drivers for common hardware, such as printers, will be scarce when the OS debuts.

"People should not expect to take all of their existing hardware, get one of these 64-bit systems [both OS and PC], and get everything to run," says Greg Sullivan, Windows XP lead product manager. However, as with previous Windows releases, there will be some drivers bundled with the OS.

Expect no big marketing displays at your local CompUSA for this Windows' debut: It will be an option for new PCs once it ships, but it won't be offered at retail. Sullivan says Microsoft is working on ways to distribute it to users who buy early 64-bit PCs (most likely via a CD, and not free).

What about the next version of Windows, code-named Longhorn? When it arrives (unlikely before 2005), Longhorn will also come in 32- and 64-bit flavors, but even then the 64-bit version may not be offered at retail.

After the new OS launches, the transition to full 64-bit computing will likely take far longer. That's because XP 64 will benefit only those users who have 64-bit applications--which won't be in great supply, at least for the next couple of years.

Among the first 64-bit consumer apps will be high-end games such as Unreal Tournament 2003 (via a patch developer Epic Games planned to make available at Athlon 64's launch) and video encoders such as DivXNetworks' Dr. DivX (due shortly after the Athlon 64 launch; it should be bundled with higher-end Athlon 64 PCs). Accordingly, Microsoft is working hard with video-capture-card and joystick vendors to develop 64-bit drivers for their gear.

But even users who get XP 64 and the Unreal patch won't see much of a difference from the 32-bit version of the game. Tim Sweeney, Epic Games' founder and lead programmer, says the true benefits of 64-bit computing will be fully exploited only in a new generation of games (including the next Unreal) that won't ship until 2005.

IDC analyst Roger Kay says it will take at least 18 months for new apps and lower hardware prices to make a 64-bit desktop OS mainstream. "Give it time," he counsels.

Yardena Arar

64-Bit Computing According to Apple

Apple touts its new 64-bit Power Mac G5 as the world's fastest personal computer, but our initial tests indicate bragging rights may belong to PCs using AMD's Athlon 64 FX-51 chip.

Even Apple's 2-GHz dual-CPU G5 unit had a hard time keeping up with a single-chip FX-51 PC in most tests. (Tests were not exhaustive, however: Working with our sibling publication, Macworld, we selected four applications available on both platforms and then ran seven hand-timed tests. Our test suite, PC WorldBench 4, cannot run on Macs.) The new Macs aren't great values either, as the top-of-the-line G5 ($3549 as configured) costs about $200 more than the similarly configured Alienware Aurora. (Prices do not include a monitor or speakers.)

The dual-G5 sparkled in one main area: our Photoshop test, which it completed in 18 seconds, or about 17 percent faster than the Aurora's 21 seconds. The 1.8-GHz single-chip G5 ($2999) trailed at 27 seconds.

Elsewhere, the Alienware earned top marks, performing particularly well in the Premiere QuickTime test. (See chart for more detail.)

OS Ready Today

Like 64-bit Athlons, G5 CPUs (developed by Apple and IBM) can run 32-bit and 64-bit applications. However, while Athlon owners must await shipment of Microsoft's 64-bit Windows XP (or choose a 64-bit Linux OS) to use the chip's 64-bit capabilities, Mac G5 owners have a 64-bit-capable desktop out of the box.

That's because Mac G5s come with a modified version of the OS X operating system, code-named Jaguar, which works with apps that can make 64-bit requests. Later this year Apple will launch another OS revision, code-named Panther, with even more 64-bit enhancements; neither is a fully 64-bit OS.

Yet G5 owners still face one of the same hurdles as Athlon 64 buyers do: scarce 64-bit software. The most notable app available--and the most relevant to many Mac users--is Photoshop 7.0.1, which has a 64-bit plug-in that lets it make better use of G5s. But despite Apple's OS advantage, it will probably take a year or more for a sizeable number of 64-bit apps to ship for both G5 and Athlon 64, says Kevin Krewell, general manager at research firm MDR. Expect media creation apps first, he says, because that's Apple's core market, and those developers will like the larger address space.

Tom Mainelli

Athlon 64 vs. Apple G5 Systems: Not Even Close (chart)

Apple Power Macs did well on Photoshop, but the 64-bit AMD-based systems won handily on most tests.

System	Processor	Graphics memory	Hard-drive setup	Time (in seconds) required to run test						Frames per second
				Premiere 6		Photoshop 7.0.1		Word		Quake III
				Render	QuickTime	50MB image	150MB image	Search and replace	Auto summarize	1024 by 768	1600 by 1200
Apple Power Mac G5	Two 2-GHz PowerPC G5s	128MB	Standard	4	72	18	51	16	12	294	207
Apple Power Mac G5	1.8-GHz PowerPC G5	128MB	Standard	5	84	27	76	19	14	147	141
Alienware Aurora	2.2-GHz Athlon 64 FX-51	128MB	Standard	4	37	21	60	8	6	335	257
Alienware Aurora	2.2-GHz Athlon 64 FX-51	256MB	RAID	3	33	21	62	5	6	338	261
Falcon Northwest Mach V	2.2-GHz Athlon 64 FX-51	256MB	RAID	3	33	20	60	5	6	337	246
Voodoo Fury	2.2-GHz Athlon 64 FX-51	256MB	RAID	3	33	21	62	5	6	336	248
Polywell Polystation Two	2-GHz Opteron Model 246s	128MB	Standard	3	30	17	47	9	6	250	199
ABS Awesome 5100	2-GHz Athlon 64 3200+	128MB	RAID	4	40	23	68	6	7	261	224
Alienware Area 51	3.2-GHz Pentium 4	256MB	RAID	4	46	24	69	7	7	307	254
How We Test: In Adobe Premiere we timed the rendering of our workspace and timed the export of a 959-frame movie at 720 by 480 resolution and 30 frames per second into the QuickTime format. In Adobe Photoshop we timed the operation of ten filters on a 50MB image file and a 150MB file. In Microsoft Word we timed a search-and-replace of one word in a 1437-page document, and the execution of the auto summarize function on a 210-page document. We ran Quake III version 1.32's included "timedemo four" using high quality settings at two resolutions, and recorded the average frame rate. All machines were tested with 1GB of RAM and the ATI Radeon 9800 Pro graphics card; the Mac version of the graphics card has a maximum of 128MB of RAM, while the high end for PCs is 256MB. Most of the PCs used dual, RAID-striped hard drives; the Apple systems did not. We retested the Alienware Aurora with the 128MB Radeon 9800 Pro card and without RAID for more-direct comparison with the G5 systems. Tests on PCs performed by the PC World Test Center; tests on Apple systems performed by the Macworld Test Center. All rights reserved. Chart Notes: In Quake III, higher is better; elsewhere, lower is better. Best scores in bold.