By Jeremy Cook
Data centers consume vast amounts of electricity. That consumption is a reasonable tradeoff for the modern informational conveniences we easily take for granted. However, a dramatic rise in energy prices due to international instability and inflation means that server operators are looking closely at how much power their systems use.
In addition to bottom-line cost reductions, reducing energy use has reputational benefits that are more difficult to measure but still significant. The question then becomes, "How can data centers increase their efficiency?"
These ideas may help you eke out more efficiency from your servers.
Data center processors (x86 vs ARM)
ARM processors are not historically common in server roles. But ARM architecture, prized for its power efficiency and physically integrated design (dominant in the smartphone market), is growing prevalent in general computing and server roles. The most prominent general computing examples are Apple's M1 to M3 processors, which allow for many benefits over the x86 devices more broadly implemented today.
While x86ARM is still the primary architecture used in servers today, ARM allows tightly integrated hardware implementations that result in an excellent power-to-performance ratio. Companies implementing ARM today include:
- Ampere: Semiconductor designer Ampere focuses on efficient, high-performance cloud solutions based on the ARM architecture. Released in May 2023, their flagship AmpereOne processing line features up to 192 compute cores, allowing it to handle extremely demanding applications. Ampere’s ARM architecture-based solutions have been shown to boost performance versus x86 designs while decreasing both power and rack space requirements.
- NVIDIA: Released in August 2023, NVIDIA’s ARM architecture-based GH200 Grace Hopper computing platform is “designed to do more with less.” It implements 144 ARM cores on two CPU dies, and includes a 900 GB/s chip-to-chip interconnect. The system meets the growing demands on data centers, while roughly doubling computing performance per watt.
While potential performance gains are exciting, there are still drawbacks to using ARM architecture, including fewer software options than for x86 processors. X86 has been the standard for years — many server and general computing applications are written for it. While the x86 paradigm still presents an attractive option, if energy efficiency is paramount, then the ARM architecture is worth fresh consideration. It may grow from a niche server option to something more mainstream.
Power supply efficiency
Typical power supplies take AC power (e.g., 120VAC) and invert/step it down to 12VDC, 5VDC, and 3.3VDC for computing use. This sort of inversion/conversion inherently involves energy loss, but the level of loss depends on the quality of the power supply. Fortunately, power supplies have improved. Their efficiency is indicated by an "80 Plus" rating. The 80 Plus moniker referred to an 80% or higher conversion efficiency at the program's launch in 2004. As supplies improved, this was extended to different colors indicating how much better they are than 80%.
For a conversion/inversion from 115 volts, several 80 Plus ratings are as follows:
- 80 Plus White (standard): at least 80% efficient through its operating range.
- 80 Plus Gold: at least 87% efficient at 20% load, 90% efficient at 50% load, 87% efficient at 100% load.
- 80 Plus Titanium: at least 90% efficient at 10% load, 92% efficient at 20% load, 94% efficient at 50% load, 90% at 100% load.
From a cost/benefit standpoint, system designers must consider which supply efficiency works best for their purpose. For instance, an 80 Plus Gold supply runs at 90% efficiency at a 50% load, so if the choice is between a larger Gold supply running at optimum efficiency versus a smaller Titanium supply running at 90% efficiency when 100% loaded, the Gold option might be preferable. In this case, the Gold option would also allow for more power that could be applied in the future, though potentially at a lower efficiency.
48VDC data center power management option
As mentioned, servers are traditionally powered by AC power that's stepped down and inverted to 12VDC to feed processors, RAM, and other computing elements. System designers have long considered the type of AC power used (e.g., 120VAC versus higher voltages), but a newer trend is to use 48VDC for power distribution, which is then stepped down to 12VDC closer to where it is used. The 48VDC method provides a much easier transition than the full step down/inversion from 120VAC and can be more efficient from an electrical power and systems density perspective.
Creative solutions for data center cooling energy efficiency
Servers create a lot of heat that needs to be extracted. Power supplies and 48VDC distribution present efficiency options that can mean lower heat generation. A 1U server rack configuration versus the more spacious 2U design can also be considered. The 2U design allows more space for cooling, along with larger, potentially more efficient components, though the specific implementation will dictate what actual cooling and efficiency benefits are realized.
Geography can also be a factor. Servers located in a chilly climate may require less cooling. Besides simply expelling the heat, servers in these environments can even pump hot air into a city's heating grid, similar to how two-way electrical metering allows homeowners to send excess energy to the electrical power grid. Depending on the location and infrastructure available, it may be possible to turn this waste heat into an energy resource that offsets some spending on the energy input side.
Data center efficiency options
While electricity increases in price, new solutions are continuously developed, such as 48VDC power distribution and ultra-efficient power supplies. Novel solutions and proven data center energy best practices typically require a capital outlay. Still, with increasing energy prices and environmental concerns, new equipment can be more easily justified, positively contributing to a company's bottom line and reputation.
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