In the North American data center industry, one number is becoming increasingly glaring: electricity costs. Industrial electricity prices at major U.S. data center hubs generally range from 8 to 15 cents per kilowatt-hour, and as the power density of AI training clusters continues to rise, differences in optical module power consumption are transforming from a technical parameter into a financial variable.
Many procurement teams, when evaluating 800G optical modules, habitually use “cost per Gbps” as the core comparison metric. This metric itself is not wrong, but it reflects only part of CAPEX and completely ignores the fastest-growing part of OPEX—electricity and cooling.
Let us do a simplified calculation. Assume a medium-sized data center deploys 5,000 800G optical modules. If the standard DSP-based solution is chosen, power consumption per module is about 14W; if the LPO (linear-drive pluggable optics) solution is chosen, power consumption per module is about 5W. The 9W difference may not seem large, but 5,000 modules multiplied by 9W equals a continuous power difference of 45 kilowatts. At 10 cents per kilowatt-hour, electricity costs alone differ by about $39,000 per year, totaling nearly $200,000 over five years. This does not yet include the cooling power consumed by the cooling system for that additional 45 kilowatts—in a data center with a typical PUE of 1.3, cooling costs would increase by about another 30%.
This is not theoretical speculation. Industry research has confirmed that optical modules using LPO architecture have a significant power consumption advantage over traditional DSP solutions. By removing the DSP chip, LPO hands signal processing directly to the switch ASIC’s SerDes. This not only reduces power consumption to the 4W to 6W range, but also compresses latency to within 10 nanoseconds, which is particularly critical for InfiniBand and RoCE scenarios in AI training clusters.
Of course, LPO is not without cost. It places higher signal integrity requirements on the host ASIC’s SerDes and requires extensive interoperability testing to ensure compatibility with different switch platforms. When evaluating LPO solutions, procurement teams should not only look at the module’s own datasheet, but also confirm whether the supplier has completed actual verification on mainstream switch platforms such as Cisco, Arista, or NVIDIA.
Silicon photonics offers another balance. By integrating the optical engine on a silicon-based chip, silicon photonics modules have a cost advantage over transmission distances of 500 meters to 2 kilometers, with power consumption typically between 7W and 9W. However, procurement requires focused evaluation of the reliability of the laser source (CW or VCSEL) and the compliance of the external laser source (ELS), because the laser in a silicon photonics module is usually not inside the module but introduced externally through optical fiber, which imposes new requirements on data center cabling architecture.
So how should procurement teams build a practical TCO evaluation framework? The core is to expand the evaluation dimension from “unit price” to “five-year total cost,” specifically covering four layers: module procurement cost, electricity consumption cost, incremental cooling system cost, and operations and replacement costs caused by compatibility issues. The last item is the most easily underestimated—most problems that third-party optical modules encounter in the field are not optical-layer failures, but port anomalies caused by inconsistent CMIS protocol stack implementations. A module that performs perfectly in the lab may, if it frequently triggers link flapping or packet loss in actual deployment, incur hidden O&M costs far exceeding the price difference of the module itself.
For North American operators making 800G procurement decisions, it is recommended to quantify the above four dimensions into the same evaluation table when comparing prices, and to require suppliers to provide dynamic test reports on mainstream switch platforms, especially actual data for key metrics such as TDECQ and Pre-FEC BER. A responsible supplier should be able to provide evidence that TDECQ is controlled below 2.2dB in factory test reports and that Pre-FEC BER remains stable within the 10⁻⁶ to 10⁻⁵ range during a 72-hour full-load stress test. These data are more persuasive than any marketing rhetoric.
