Intel and AMD square off

Most organizations have a core of demanding users—software developers, researchers, graphic artists—who want the fastest computers available. For them, advances in PC technology can't come soon enough.

The good news for those users is that both Intel Corp. and Advanced Micro Devices Inc. (AMD) have been pushing the pedal to the metal. The latest processor from Intel, the Pentium 4, is the fastest the company has produced. At speeds topping out at 1.5 GHz, it runs at up to twice the clock speed of the typical business PC processor, the 750 MHz Pentium III. AMD has just shipped the 1.2 GHz Athlon processor, the latest in the series developed under the code name Thunderbird.

Be aware that you can't use these new processors to upgrade existing PCs. You'll have to buy an entirely new system because both processors require new supporting chipsets.

The Pentium 4 processor is not merely a faster Pentium III but a substantial reworking of Intel PC processor technology. The front-side bus (FSB)—the high-speed data conduit interconnecting the CPU, memory and peripheral control chips—was boosted from 133 MHz to 400 MHz. Cache, the extremely fast memory that's part of the CPU chip, has been tweaked for speed and given smarter logic to predict what your software will try to do next. Internal miniprocessors called arithmetic logic units run at twice the CPU's clock speed—a PC first.

The Pentium 4 is clocked from 1.3 GHz to 1.5 GHz. Standard PC memory can't transfer data fast enough to keep up with a 400 MHz FSB, so the Pentium 4 requires the use of Rambus dynamic RAM (RDRAM). With transfer rates of up to 3.2 gigabytes per second (G/sec), RDRAM is the fastest memory architecture available for PCs. That speed comes at a price. The least expensive RDRAM board we found was about four times the cost of a high-grade, standard PC memory board.

The CPU chip fits a new type of socket that only accommodates the Pentium 4, and the RDRAM board fits only in systems built for it. Some Pentium III machines use RDRAM, but it is made at three speed levels: PC600, PC700 and PC800. Only RDRAM units with matching speed ratings are interchangeable.

AMD's latest Athlon chip is a relatively minor update to previous Athlon CPUs, but all Athlons have architectural advantages over the Pentium III. The latest Athlon's main benefit is a 266 MHz FSB. Like Intel, AMD had to shift to a new memory architecture to accommodate this speed. DDR (double data rate) memory transfers data twice as fast as standard memory. The 266 MHz DDR memory, dubbed PC2100 because its maximum transfer rate is 2.1 G/sec, is currently quite rare and as expensive as PC800 RDRAM. However, the next lower grade of DDR memory, PC1600, debuted at a high price and has now fallen to standard memory price levels.

Like the Pentium 4, the new Athlon chip is incompatible with previous systems. It, too, uses a new type of CPU socket. The DDR memory won't fit in existing PCs and comes in multiple speed grades that must be matched. It's remarkable how close the Pentium 4 and the new Athlon are when it comes to performance. You might expect the Pentium 4, with its markedly higher clock speed, revamped design and 400 MHz FSB, to trounce the Athlon. In our tests, however, the systems performed within a hair's breadth of each other, except with regard to disk performance.

We ran the BAPCO SYSmark 2000 application benchmark on reference machines supplied by Intel and AMD. The hardware configurations were as close as could be. The Pentium 4 platform had 256M of PC800 RDRAM, a 30G IBM Corp. Ultra ATA/100 hard drive and an NVidia Corp. GeForce2 Ultra graphics adapter. The Athlon platform had 256M of PC2100 DDR memory, an identical 30G IBM Ultra ATA/100 hard drive and an NVidia GeForce2 graphics adapter (not the faster Ultra model). We loaded both systems with Windows 2000 immediately before running the tests.

The Intel system turned in a SYSmark rating of 219. The AMD system scored higher, with a 236. The margin for Athlon was consistent across multiple test runs but is too narrow to be considered decisive. A simple test to measure baseline memory performance handed Intel a narrow victory: 615 megabytes per second (M/sec) compared with 559 M/sec for AMD.

The test that put the greatest distance between the systems measured disk throughput. Using a sequential file-access benchmark, the Pentium 4 system wrote data at 15.3 M/sec and read data at 29.9 M/sec. The Athlon machine's write speed was 18.5 M/sec and its read speed was an impressive 37.7 M/sec. Keep in mind that the same IBM hard drive was used in both systems.

The benchmark results suggest that core performance is a virtual tossup: the Athlon CPU computes faster, but the Pentium 4's Rambus memory architecture transfers data to and from memory more rapidly. On balance, we rate their performance as comparable.

The wider gap in disk performance suggests a potential disadvantage for Intel's chipset. The Intel 850 chipset handles Ultra ATA/100 disk input/output (I/O) for the Pentium 4, while the AMD test system uses a blend of AMD and VIA Technologies Inc. chipsets for that purpose. This test is significant for desktop configurations, but even entry-level servers are likely to use SCSI hard drives. If disk I/O is shifted from the motherboard's chipset to an add-in SCSI controller, this performance gap will probably evaporate.

The first crop of Pentium 4 and 1.26 GHz Athlon desktop systems will sell for around $2,000. Pentium 4 desktops are already available, and Athlon 1.2 GHz desktops equipped with a 200 MHz front-side bus and PC1600 DDR memory are shipping now. The newer 266 MHz bus models will take another few weeks to show up in the market.

While many in your organization might want the fastest PC on the market, few actually need it. For most users, the performance of a 1 GHz Athlon or a 1 GHz Pentium III will more than suffice. Those systems cost considerably less—a typical desktop configuration runs about $1,250—and they have the benefit of sharing standard PC133 memory.

Organizations that want to stock just one type of memory for all new PCs are probably better off with AMD for now; the company has no plans to use Rambus memory. However, by this time next year, Intel will support the use of DDR memory with Pentium 4 processors.

Yager is a freelance journalist. He can be reached at [email protected].


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