Advanced Micro Devices Inc. (AMD) will precede rival Intel Corp.'s midyear product launches with four new Athlon 64 processors, expected to be introduced Tuesday at the Computex exhibition in Taipei.

The Athlon 64 3800+, 3700+, and 3500+ are faster versions of the mainstream Athlon 64 product family. The Athlon FX-53 is a specialized Athlon 64 chip that caters to a small group of PC users that demand the most performance available.

AMD changed the packaging technology for the Athlon 64 3800+, the 3500+ and the Athlon FX-53. Those processors now use 939 pins, unlike previous versions of the Athlon 64 family that used 754 pins and previous FX chips that used 940 pins.

The pins on a processor connect the chip to the wiring of the motherboard. In order for the Athlon 64 processors to take advantage of dual-channel DDR (double data rate) memory modules, AMD needed to increase the number of pins to accommodate the wider memory channels.

It did just that in earlier versions of the Athlon FX-51 and FX-53 that used 940 pins with dual-channel memory controllers, the same design as the Opteron server chip. This design, however, requires expensive registered memory chips normally used in servers because of their performance and reliability attributes. They use registers, or temporary holding places for data, to store data for one clock cycle before moving it along.

The 939-pin design allows Athlon 64 users to get dual-channel memory performance without having to pay extra for the registered memory chips, said John Crank, senior brand associate for desktop product marketing at AMD.

The 3700+ chip kept the 754-pin design, and therefore can only work with single-channel memory chips. AMD will offer both 940-pin and 939-pin versions of the Athlon 64 FX-53 as long as there is demand for both chips, Crank said. Users who bought 940-pin versions of the chip would need to purchase new motherboards in order to use the 939-pin chip.

The 3800+ and 3500+ chips are based on the Newcastle core, which features 512K bytes of Level 2 cache, Crank said. Athlon 64 chips based on the older core technology, such as the new 3700+ chip, come with 1M-byte of cache, he said. A processor with more cache can store larger amounts of frequently accessed data close to the processor for fast retrieval.

To balance out the reduced cache, AMD increased the speed of the Hypertransport bus within the 3800+ and 3500+ chips to 2GHz, compared to 1.6GHz in the 3700+ chip based on the older core technology, Crank said.

The new Athlon 64 processors will help AMD compete against faster Prescott Pentium 4 processors and the Grantsdale chipset expected from Intel Corp. later this quarter. Grantsdale will come with support for the new PCI Express interconnect standard that will help improve system performance.

The performance of AMD's new processors should be very competitive with Intel's new Prescott Pentium 4 and Pentium 4 Extreme Edition processors, but obtaining an exact comparison of the performance of each product line is a difficult undertaking, said Kevin Krewell, editor in chief of the Microprocessor Report.

"It's a real horse race between the two (companies)," Krewell said. Each company can point to certain applications in which its processor outperforms the competition, he said.

The new chips should also help AMD maintain its recent success in the retail market. Hewlett-Packard Co.'s and Gateway Inc.'s eMachines division have prominently featured AMD desktops and notebooks in their retail channels. Intel still leads the overall market by a wide margin, but AMD is gaining ground in categories outside the value PC segment where it has seen the most success, according to analysts.

The Athlon 64 processors can run both 32-bit and 64-bit applications on a PC or workstation with a 64-bit operating system. There are 64-bit versions of Linux available for PCs with the processor, but very few 64-bit desktop applications are currently available.

Microsoft Corp.'s Windows XP 64-bit Edition for 64-bit Extended Systems operating system is expected to generate more development of 64-bit desktop applications when it is released in the fourth quarter.

The four chips are available immediately worldwide. In quantities of 1,000 units, the FX-53 costs US$799, the 3800+ costs $720, the 3700+ costs $710, and the 3500+ costs $500.