Unexpected consequences of shrinking the lithography in CPU designs have cropped up over the past decade, with the 32nm 2011 Sandy Bridge (Cougar Point) designs subject to I/O performance degradation over time, a problem that cost Intel $1 billion in manufacturing stoppages and warranty replacements. Issues in the LPC clock with the 22nm Silvermont design resulted in systems “[experiencing] inability to boot or may cease operation,” were disclosed in late 2016—three years after the affected CPUs shipped—resulting in product failures in embedded systems.

SEE: The ethical challenges of AI: A leader’s guide (free PDF) (TechRepublic)

The Silvermont bug—otherwise referred to as the Atom C2000 bug—resurfaced on Monday as Tom’s Hardware reported on an Intel Product Change Notification (PCN) indicating that Intel was refreshing the Apollo Lake Celeron N3350, J3355, J3455, and Pentium N4200 processors due to issues similar to those in Silvermont. This resulted in concern from owners of Synology NAS devices, as current Synology systems utilize Apollo Lake processors, and the company was among the hardest hit with the Silvermont bug, prompting a 1-year warranty extension for affected units.

The issue, as described in Intel’s now-retracted PCN:

On the Processor: Intel will start transitioning from B-1 stepping of the Intel Celeron N3350, J3355, J3455 Processor and Intel Pentium N4200 Processor to F-1 stepping. The new F-1 stepping SKUs will be replacing the B-1 stepping Celeron N3350, J3355, J3455 processors and Pentium N4200 processor on the Internet of Things (IOTG) roadmap for IOTG customers.

Customers may begin transitioning all production off of the B-1 stepping and on to F-1 stepping as early as September 03, 2019 and must fully transition to F-1 no later than February 28, 2020. The F-1 stepping Celeron N3350E, J3355E, J3455E processors and Pentium N4200E processor have been developed for long life manufacturability to meet the IOTG 15-year availability of Apollo Lake processors. The F-1 stepping Celeron N3350E, J3355E, J3455E processors and Pentium N4200E processor is validated for PC Client Use condition only.

Intel identified an issue with the Low Pin Count (LPC), Real Time Clock (RTC), SD Card interfaces on Intel Celeron N3350, J3355, J3455 processors and Intel Pentium N4200 processor resulting in degradation of these signals at a rate higher than Intel’s quality goals after multiple years in service.

The original PCN “had inaccurate information,” according to an Intel spokesperson, who noted that a revised version has now been published. Further, Intel provided a comment on the discrepancy:

There are no changes to the B-1 Stepping of the Intel Celeron N3350, J3355, J3455 Processors and Intel Pentium N4200 Processor as they meet all Intel quality goals for PC Usage and will continue to be available. The F-1 Apollo Lake Intel Celeron N3350, J3355, J3455 Processors and Intel Pentium N4200 Processor meet all Intel quality goals for PC Usage.

With IOTG’s operational decision to converge onto a single package for all of the IOTG Apollo Lake Processors, the F-1 stepping Celeron N3350, J3355, J3455 Processors and Pentium N4200 Processor has a slight increase in Z height compared to the B-1 Stepping.

Certainly, Pentium and Celeron devices are rarely used for enterprise deployment of primary workstations. Pentium N4200-powered netbooks are widely produced by HP and Lenovo for the consumer market, though the affected Celeron and Pentium processors are widespread in business for Internet of Things (IoT) devices, including NAS devices from Synology and QNAP that are popular among SMBs and prosumers. IoT devices that ship with these processors are typically used in always-on scenarios, which quite rightly prompts concerns when LPC flaws are discovered.

TechRepublic is seeking clarification on Intel’s definition of “PC Client Use” validation and how this definition impacts always-on scenarios for IoT, and will update this story if/when Intel provides a response.

Update: In a statement, Synology “confirmed with the chipset vendor [Intel] that all of the related product designs conform to the vendor’s latest design guidelines (July, 2019). Meanwhile, Synology has not observed any abnormal error rates since the initial release of the related products.”

Update 2: Intel provided this statement to TechRepublic:

Intel originally published a specification update in July 2017 outlining mitigations for Errata APL47 to avoid signal degradations under certain conditions in the outer years of use. When the B-1 Stepping is used in accordance to the published specifications and design guidelines, it meets PC Client Usage requirements. With the F-1 Stepping, the mitigations mentioned in Errata APL47 are no longer required to meet PC Client Usage requirements.

Further, Intel noted that the errata information indicates the issue was fixed in firmware. It’s unclear what performance impact this update would have on the affected low-power processors.

For more, check out “Spectre and Meltdown explained: A comprehensive guide for professionals” and “10nm Intel CPUs not coming to desktops until at least 2022, amid manufacturing issues” on TechRepublic.

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