Dual core processors work best when software can run in parallel on them. So-called 'multithreaded applications' benefit from an additional CPU core because subroutines can be allocated to different arithmetic and logic units. Administering the threads carries an overhead, though, which means that dual core processors are never exactly twice as fast as their single core counterparts.
Chip-makers AMD and Intel have released dual core processors aimed at users who need high arithmetic performance and use mainly multithreaded applications. Programs such as CAD/CAM and audio or video processing benefit particularly from a second processor core. However, AMD and Intel's dual core chips for this market cost between $500 and $1,000, and are therefore much too expensive for the mass market. .
Dual core and the office
Relatively little multithreaded software is used on standard office and home computers, so the purchase of a high-end dual core processor is rarely justified. Having said that, mainstream users can benefit from dual core technology. If several applications are active at the same time and certain tasks are stalled, then a dual core chip is worth having. For example, a hard disk defragmenter may be running in the background, leaving insufficient resources for a foreground application like a presentation. Similar effects can occur when antivirus or anti-spyware scans are active in the background. In these circumstances, a dual core chip can be very helpful even on a standard office PC.
When you consider what's going on beneath the surface of a typical office PC in a larger enterprise, it's arguable that a dual core processor can be justified here, too. Applications installed by the IT department can create a multitude of processes -- these may not always be active, but it's almost inevitable that at some point a crucial productivity task (finishing a presentation, for example) will be held up by a lack of computing resources.Now that both Intel and AMD have affordable dual core processors available (the $241 Pentium D 820 and the $328 Athlon 64 X2 3800+ respectively), there's little to stop this technology being widely adopted.