The desktop PC will begin getting a makeover in the second half of 2004, with the movement creating "tumultuous transformations" in the PC industry, according to a new study.

The changes, said Joe D'Elia of market-research firm iSuppli, will be driven by hardware form factor and interface improvements. "The year 2004 will bring tumultuous transformation to the market that will forever alter the nature and appearance of PCs," said D'Elia. "PC and motherboard makers [will] flood the market with a host of new products in 2004."

D'Elia, iSuppli's PC market director, said the changes will bring smaller, more-robust desktops that offer major benefits to business users, because the result will be a smaller footprint on the desktop. Combined with flat-panel screens, the new PCs will leave desks with more space.

A series of developments are combining to bring about the changes, with most of them centered on the new Balanced Technology Extended interface, said D'Elia. The BTX interface specification provides a flexible standards-based form factor foundation that supports the implementation of new desktop technologies, including PCI Express and Serial ATA.

In addition, a move away from the PCI and AGP buses to the single PCI Express bus will come into play, as PC interfaces among processors, memory, and drives will work more efficiently together. With its 66-MHz speed, the PCI bus performed well when PC processors were in the 100- to 200-MHz range.

"The interfaces have been out of sync for some time," said D'Elia. "The processors have had to wait for the buses to catch up." PCI Express, a serial bus, will bring all the interfaces closer in data-exchange speeds and lead to radically new socket and board layouts. "The acceptance of BTX as the main standard will mean that parts for smaller PCs will be available off the shelf. Thus, smaller PCs ultimately will become the norm, with associated cost reductions making them acceptable in the mainstream market."

The smaller and more power-efficient PCs will find new places in living rooms. D'Elia said they will be small enough to fit on top of a typical audio-components rack. Also, since the BTX spec establishes improved management of the thermal envelope in PCs, the number of fans can be lowered. "If you want to move the PC from the den or home office to the living room," D'Elia said, "you're not going to put up with a half-dozen fans creating a howling gale."

There are major changes coming in disk and memory interfaces, too. Serial ATA will replace the aging ATA drive interface. D'Elia says that in business applications, serial ATA and serial attached SCSI will replace the workhorse SCSI interconnection. As for memory, Double data rate will be phased out by DDR2 memory technology. Virtually all the changes--most enabled by the BTX spec--will bring about smaller PCs with improved power management and wholesale socket and connection changes. As a result, desktops will likely be half the size of today's machines.

D'Elia sees a "good news-bad news" scenario in all this. The bad news is there will be a major disruption in the supply chain, as motherboards and components change dramatically; the good news will come in the form of opportunities for new suppliers and players to enter the field during the period of upheaval.