Intel finally finds the “root cause” of Raptor Lake CPU instability
Intel finally uncovers the root cause of Raptor Lake’s “Vmin Shift Instability” issue
Intel believes they have finally uncovered the “root cause” of their 13th/14th Generation Raptor Lake instability problem. In a new update on the issue, Intel revealed that it was caused by “a clock tree circuit within the IA core which is particularly vulnerable to reliability aging under elevated voltage and temperature.”
Now that Intel has uncovered the root cause of Raptor Lake’s ongoing instability saga, the company can issue final fixes that should prevent more affected CPUs from becoming unstable. Furthermore, this allows Intel to again confirm that their new Lunar Lake and Arrow Lake CPUs are unaffected by this issue.
Intel has localized the Vmin Shift Instability issue to a clock tree circuit within the IA core which is particularly vulnerable to reliability aging under elevated voltage and temperature. Intel has observed these conditions can lead to a duty cycle shift of the clocks and observed system instability.
Intel has also stated that new microcode will be released to further mitigate Raptor Lake’s “Vminshift” issue. This new update is called “ox12B”, and it will be made available to the public soon.
Intel has identified four (4) operating scenarios that can lead to Vmin shift in affected processors:
- Motherboard power delivery settings exceeding Intel power guidance.
a. Mitigation: Intel Default Settings recommendations for Intel Core 13th and 14th Gen desktop processors.- eTVB Microcode algorithm which was allowing Intel Core 13th and 14th Gen i9 desktop processors to operate at higher performance states even at high temperatures.
a. Mitigation: microcode 0x125 (June 2024) addresses eTVB algorithm issue.- Microcode SVID algorithm requesting high voltages at a frequency and duration which can cause Vmin shift.
a. Mitigation: microcode 0x129 (August 2024) addresses high voltages requested by the processor.- Microcode and BIOS code requesting elevated core voltages which can cause Vmin shift especially during periods of idle and/or light activity.
a. Mitigation: Intel is releasing microcode 0x12B, which encompasses 0x125 and 0x129 microcode updates, and addresses elevated voltage requests by the processor during idle and/or light activity periods.
Intel has stated that its new 0x12B microcode will not reduce the performance of its Raptor Lake series CPUs. Intel’s testing confirms that its performance impact is “within run-to-run variation.”
Regarding the 0x12B update, Intel is working with its partners to roll out the relevant BIOS update to the public.
Intel’s internal testing comparing 0x12B microcode to 0x125 microcode – on Intel Core i9-14900K with DDR5 5200MT/s memory – indicates performance impact is within run-to-run variation (ie. Cinebench* R23, Speedometer*, WebXPRT4*, Crossmark*). For gaming workloads on Intel Core i9-14900K with DDR5 5600MT/s memory, performance is also within run-to-run variation (ie. Shadow of the Tomb Raider*, Cyberpunk* 2077, Hitman 3: Dartmoor*, Total War: Warhammer III – Mirrors of Madness*). However, system performance is dependent on configuration and several other factors.
Intel reaffirms that both Intel Core 13th and 14th Gen mobile processors and future client product families – including the codename Lunar Lake and Arrow Lake families – are unaffected by the Vmin Shift Instability issue. We appreciate our customers’ patience throughout the investigation, as well as our partners’ support in the analysis and relevant mitigations.
It has taken months for Intel to uncover the root cause of their Raptor Lake CPU instability issues. These issues have greatly damaged the company’s reputation. Intel now has a lot to prove with Arrow Lake. They need Arrow Lake to be a success to rebuild their reputation and improve their financial position. Expect Intel’s next-generation Arrow Lake CPUs to launch next month.
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