Network Engines (NEI)

[blueskywaves]

The heat is hot..........

Dell says overheating may limit the blade market's growth, but other vendors disagree
By Larry Greenemeier and Jennifer Zaino

Blade servers are hot. Maybe too hot, according to Dell Computer president and chief operating officer Kevin Rollins. Blades densely packed in a chassis generate excess heat, Rollins warned last week, and potential problems with heat dissipation could stunt growth in the blade-server market.

Blade technology "may not pan out" as well as expected, Rollins said at InformationWeek's Spring Conference. "It's great technology," he said, but concerns are growing about how to cool blades as more powerful, next-generation processors enter the market. "There isn't an obvious solution" to the problem, he said, noting that it's expensive to ventilate and cool densely packed systems. "So the market for blades may be smaller than thought," he added. This would be a blow to the server market, which has not seen much growth in recent years.

"There isn't an obvious solution" to the problem of keeping blade servers cool, Dell president Rollins says.

Sales of blade servers are expected to increase dramatically, from $341 million this year to $3.7 billion by 2006, according to IDC estimates. The research firm hasn't changed its projections based upon heat-dissipation concerns.

But Rollins isn't alone in his concerns about the technology. "Already the failure rate in the top third of server racks is three times the bottom two-thirds," says Kenneth Brill, executive director of the Uptime Institute, a research and consulting firm that specializes in data-center management. "Blades will further exacerbate this problem." Overheated servers can slow throughput and affect system reliability.

http://www.informationweek.com/story/IWK20030307S0034

Note that blade servers usually have to use the fastest processors possible. Storage blades have different design considerations depending on whether these are used for transactional data (DAS/SAN), collaboration data (NAS) or reference data (Centera).

Each Centera module, for example, uses a lowly Pentium III processor running Linux to manage four (4) 250GB disk drives from Maxtor and three (3) NICs (network interface cards). The semiconductor content of a typical disk drive is probably over 40% by now so the speed of the processor is effectively gated by the overall system "heat budget" which includes the heat profile of all those other components inside each box.

From NENG Patent Number 6,512,673 issued on January 28, 2003....

BACKGROUND OF THE INVENTION

The present invention relates to digital data processors, and, in particular, to methods and apparatus for cooling components within a digital data processor or ancillary device. The invention has particular application in compact, "low profile" devices where space is at a premium, airflow paths are restricted and overheating is of concern.

Heating is a constant and significant problem in digital data processors. The failure rates of many electronic components increase as operating temperatures rise. This is particularly true of central processing units which, themselves, often generate significant heat. The problem is compounded by the use of more densely packed circuit boards, by faster processor chips, and by the large power supplies needed to support the foregoing.

Most often, processors and associated components are cooled by airflow. Fans are typically used to push or pull air from one side of a chassis, across the components, and out the other side of the chassis. Thus, for example, a typical digital data processor includes chassis intake and/or exhaust fans, often with a fan on the central processing unit itself. While the steps of simply providing intake and exhaust fans on a chassis or housing wall, and of providing one or more device fans on critical components, have proven adequate to date, there remains a need to provide for the cooling of even more powerful, and/or more compact systems.

One object of the present invention is to provide an improved digital data processor apparatus and methods.

A more particular object is to provide such apparatus and methods for cooling components of digital data processors

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search....

The view from Japan................

World's First Water-Cooled Desktop PCs: Developed by NEC Using Hitachi Technology
June 23, 2003 (TOKYO) -- NEC Corp released a desktop personal computer equipped with a water-cooled heat dissipation system in May.

This was the first time that a leading PC vendor has commercialized a water-cooled desktop model.

In the laptop market, however, water-cooled products from Hitachi Ltd already are on sale. NEC's water-cooled module for desktop computers was developed in collaboration with a Taiwanese parts manufacturer licensed to use Hitachi's technology.

Overtaken in the Laptop Market

NEC originally intended to develop its own water-cooled module for PCs, to counter the problem of increasing noise from the cooling fan as microprocessors get faster and generate more heat. At some stage, conventional air cooling will be unable to cope with the heat, the company said.

Thus, in December 2001, serious development work began at NEC, utilizing the results of water-cooling R&D previously undertaken at the company's in-house research labs. The engineering team was eager to come up with a suitable design.

But just three months later, in February 2002, Hitachi unveiled its water-cooled laptop prototype. It was not a welcome sight for Hiroshi Sakai, manager, BB&M R&D division of NEC CustomTechnica, Ltd.

"Although we were disappointed, the Hitachi laptop definitely had a bearing on the development of our desktop models," said Sakai.

According to its original plan, NEC intended commercial release of water-cooled desktop PCs from 2004. But that was going to be too late. NEC gave up in-house development and decided instead to deploy Hitachi's water-cooling technology. It would concentrate on releasing a water-cooled desktop computer before another company did so. Because speed was of the essence, design of the water-cooling module, safety assessment, and case design were all conducted simultaneously.

Use of a Cooling Fan the Main Point of Difference

The water-cooling module developed by NEC and its Taiwanese partner works as follows. A cooling solution is fed by a centrifugal pump to a water-cooling jacket that absorbs heat from the microprocessor. The heated solution then flows into a radiator where the heat is released. A cooling fan cools the radiator, venting the hot air outside the computer case.

Hitachi's technology is utilized in components such as the cooling solution and the flexible tube used in part of the flow path. The maximum discharge capacity of the centrifugal pump is set four times higher than the pump used in Hitachi's laptops. Cooling capacity is a maximum of 75W.

The main difference between NEC's desktop design and Hitachi's laptop water-cooling mechanism is the use of a fan to cool the radiator. In the Hitachi laptops, the tube that circulates the cooling solution is fixed to the casing at the back of the LCD panel, and heat is dissipated by natural convection. In a desktop model, though, a tube would be difficult to attach and detach, and any possibility of upgrading the hardware would have to be sacrificed. The whole computer could overheat drastically too.

The laptop water-cooling design would be infeasible for a desktop PC.

Noise Held Down to 33dB(A)

Instead of dispensing with a cooling fan as in Hitachi's laptop models, NEC's solution was to retain the fan that cools the power supply unit. The fan would also serve to circulate air inside the computer, dissipating heat from the microprocessor at the same time. That is, the role of the water-cooling technology would be to efficiently transport heat away from the microprocessor, nearer the power supply unit.

However, the fan for the power supply unit was made larger than usual. The fan diameter was increased to 12cm, lowering the maximum speed from the normal 2,600rpm to 1,200rpm. This resulted in a much reduced noise level.

The pipe, reserve tank, and water-cooling jacket are all made of copper, an excellent heat conductor. This is to enhance the effect of the natural heat dissipation from parts other than the radiator, lessening the load on the cooling fan as much as possible. With these measures, the noise level is reduced to a maximum of 33dB(A). In air-cooled PCs of equivalent performance, the noise level is about 43dB(A).

Also, NEC considered ways to prevent water leaks. The centrifugal pump, being less shock-resistant than other parts, was of greatest concern. So the pump is encased in a plastic cover, with a humidity sensor placed inside. When the sensor detects a leak, the computer is forcibly powered off.

Water-Cooling Technology Advancing into the Home

Water-cooling technology for PCs is steadily growing in application. In October 2002, Toshiba Corp unveiled a prototype water-cooling module designed for laptop computers. Commercialization is expected before year-end, according to the company.

On May 28, Hitachi Cable, Ltd announced a desktop-computer water-cooling module with a cooling capacity of 150W. The module is due for release in the first half of 2003.

In the future, water-cooling technology will not be limited only to PCs. Hitachi cites a wide range of equipment in which the technology could be applied, including copiers, liquid-crystal projectors, plasma display panel (PDP) TVs, and game consoles. For devices used in home living rooms in particular, water-cooling technology that reduces fan noise sounds like good news, indeed.