New Power Mac uses liquid cooling on high-end model

Apple Computer Inc. launched new Power Mac systems featuring the 64-bit G5 processor Wednesday, including a model that uses liquid cooling technology.One of the new Power Mac G5 systems is Apple's first Power Mac with IBM Corp.'s new 90-nanometer PowerPC 970FX chip, which runs at 2.5GHz and features a 1.25GHz front-side bus. A total of three dual-processor configurations are available for order through Apple's Web site or the company's retail stores; the other two configurations use older PowerPC processors.

The high-end 2.5GHz Power Mac system features liquid cooling to remove heat from the processor. All PCs use some type of cooling technology, but most use a fan. Liquid cooling technology is generally found in high-end gaming PCs or special systems for high-performance computing or scientific applications.

The new 970FX processor is much smaller than its 0.13-micron predecessor, which means the heat from the CPU (central processing unit) is more concentrated, said Tom Boger, senior director of product marketing for Apple. The new chip is consuming roughly the same amount of power as the older chip, and a more sophisticated system is needed to remove the heat from the processor die.

Apple is using a closed-loop liquid cooling system comprised mostly of water with some propylene glycol, Boger said. It is transparent to the user and maintenance-free, he said.

Apple first used the PowerPC 970FX processor in an update to its XServe servers. It had hoped to ship those systems by the end of February, but didn't get them out of the door until March and blamed IBM for the delay on Apple's first-quarter earnings conference call.

IBM attributed the delays to yield issues during its own earnings conference call.

"Yield is a way of describing other issues. When something doesn't work, the yields are low," said Roger Kay, vice president of client computing at IDC in Framingham, Massachusetts.

Most chip companies find it more difficult to produce reliable chips at higher clock speeds when shifting to a new design. They can usually produce new chips at similar clock speeds to older designs, but the fastest versions of a new processor are generally available in more limited quantities or at later dates than their slower counterparts.

In fact, the dual 2.5GHz Power Macs won't ship until July, Apple said. The dual 1.8GHz and 2.0GHz models are available immediately.

The 2.5GHz system comes with two processors, 512M bytes of PC3200 (400MHz) DDR (double data rate) SDRAM (synchronous dynamic RAM), a 160G-byte hard drive, a Radeon 9600 XT graphics card from ATI Technologies Inc. with 128M bytes of DDR video memory, and a DVD-R/CD-RW optical drive for US$2,999.

The 2.0GHz was formerly the top of Apple's Power Mac line, and now sells for $500 less with a list price of $2,499, Boger said. It comes with dual PowerPC 970 processors, the 0.13-micron version of the G5 processor. It also features 512M bytes of PC3200 DDR SDRAM, a 160G-byte hard drive, a GeForce FX 5200 Ultra graphics card from Nvidia Corp. with 64M bytes of DDR video memory, and a DVD-R/CD-RW drive.

The 1.8GHz model also features the 0.13-micron PowerPC 970. It comes with dual processors, 256M bytes of PC3200 DDR SDRAM, a 80G-byte hard drive, a GeForce FX 5200 Ultra graphics card with 64M bytes of video memory, and a DVD-R/CD-RW drive