Our tests show Intel's new dual-core desktop processors should deliver some real benefit when used with software designed to take advantage of the two cores, or when you're performing multiple tasks simultaneously - virus scanning while surfing the Web, for instance.

Dual-core processors incorporate two physical processors and two Level2 memory caches into one piece of silicon, functioning, in theory, like two separate processors.

Intel's first dual-core chip, the 3.2GHz Pentium Extreme Edition 840 (which carries 1MB of L2 cache per core), goes one step further by including Intel's Hyper-Threading technology in each core, which theoretically brings you a "virtual" second processor per core.

AMD has already released its dual-core Opteron chips for workstations and servers, and its dual-core Athlon desktop CPUs are due at midyear. Unlike Intel's dual-core chips, the new AMD dual-core processors won't require new chip sets or motherboards, just a BIOS upgrade.

Like AMD's Athlon 64 chips and other new high-end Pentium EE chips, the dual-core CPU has 64-bit support.

Other dual-core desktop processors from Intel's new Pentium D line will arrive later this year and use motherboards with the forthcoming 945 chip set.

PC World tested a preproduction reference system from Intel with engineering samples of the EE 840 and the new 955X Express chip set (with 800MHz front-side bus, but alternatively it can support a 1066MHz bus); 1GB of DDR2-667 memory; and a Sapphire Radeon 850XT graphics card. The system ran Windows XP Professional.

The dual-core unit showed a slight improvement overall on PC WorldBench 5 versus the same system equipped with a 3.2GHz P4 (both with Hyper-Threading on). However, it trailed the 3.73GHz P4 EE configuration and the averages of four previously tested 2.2GHz Athlon 64 3400+ PCs and of four 2.4GHz Athlon 64 FX-53 systems (see chart).

But the new system truly showed its mettle in certain portions of PC WorldBench 5 - specifically our multi­tasking test and our media tests with Roxio VideoWave Movie Creator and Windows Media Encoder. Both applications are multithreaded, which means they can recognise and use the two cores as if they were two separate processors. On the multitasking test, the dual-core CPU produced its best result: it took just 9min 50sec to open numerous Web pages while converting video and music files to Windows Media format, whereas the single-core 3.2GHz Pentium 4 took almost 12min. It beat the Athlon systems' averages, too, and was a scant 9sec slower than the 3.73GHz Pentium EE machine.

The dual-core PC also performed well in the Windows Media Encoder and VideoWave tests.

Interestingly, we found that the dual-core unit performed better on the multithreaded applications with Hyper-Threading turned off than with the technology enabled.

Verdict: Don't expect dual-core to be the top performer today for games and other demanding single-threaded applications but that will change as applications are rewritten.

Pentium Extreme Edition 840

Price: $2099; (street pricing around $1650) VENDOR: Intel URL: www.intel.com.au SPECIFICATIONS: 3.2GHz; 800MHz FSB; 1MB of L2 cache per core; Hyper-Threading (HT) in each core; 955X Express chipset; 64-bit support

FEATURES: 9 VALUE: 5 OVERALL:7