In the battle of the new dual-core processors, AMD has beaten Intel. In tests run by PC World, AMD's new Athlon 64 X2 outdistanced Intel's Pentium Extreme Edition 840.

The tests indicated that both chips gave the biggest performance benefit when working with multiple applications at once or with multi-threaded software, designed to recognise more than one processor.

Dual-core chips build in two processing cores, in effect giving you two CPUs in a single piece of silicon. You also get two L2 memory caches, one for each core. The 2.4GHz Athlon 64 X2 4800+ chip, for example, has 1MB of L2 cache per core.

PCs with the new chips, which will come in several variations, should be available now. Also, you should be able to upgrade your existing Athlon 64 PC to the new chips with just a BIOS change, whereas to convert an Intel unit to dual-core you'll need to purchase a new motherboard.

The tests were on a reference system provided by AMD that ran Windows XP Pro. It came configured with 1GB of 400-MHz DDR memory; a 10,000-rpm, 74GB hard disk; and an Nvidia GeForce 6800 Ultra graphics card with 256MB of DDR3 RAM. The Intel test system used comparable hardware.

The AMD machine was the second-fastest PC World has ever tested, with a 116 mark on WorldBench 5, easily surpassing the 95 posted by the 3.2GHz dual-core Pentium Extreme Edition 840 reference system.

The unit showed its prowess on the multi-tasking portion of WorldBench 5. Its time of six minutes, 44 seconds was an impressive 3 minutes, 42 seconds faster than the average of two Athlon 64 FX-55 systems, and about three minutes faster than the dual-core Pentium EE 840 reference PC's time.

If you want one though, you'll have to pay dearly for it: AMD's 4800+ chips alone are priced at $1,001 each in quantities of 1000, while Intel's 3.2GHz Pentium EE 840 chips currently sell for $995. Entry-level Athlon X2 chips will cost only about half that much, however, so you can still get the benefits of 64-bit technology and dual-core processing without breaking the bank.

Intel devotees should also observe dual-core Pentium D-based systems are arriving about the time you read this, and such PCs should be considerably less expensive than those with the Pentium EE 840.