Your Ryzen CPU previously encrypted your RAM, but a firmware update discreetly disabled that feature.

      TL;DR: AMD has quietly disabled TSME memory encryption on its consumer Ryzen CPUs through firmware updates. Although the silicon still supports the feature, AMD claims it is now exclusive to PRO processors.

      AMD has surreptitiously turned off a security feature on its consumer Ryzen CPUs designed to protect against physical attacks on system memory. This feature, known as Transparent Secure Memory Encryption (TSME), encrypts all RAM data using a hardware-generated key that modifies with each boot. When enabled, it prevents cold boot attacks, DRAM interface snooping, and physical memory removal since the retrieved data remains encrypted.

      TSME had been functional on consumer Ryzen processors for several years. However, a firmware update quietly disabled it, and AMD has not provided an explanation for this decision.

      Ben Kilpatrick, a privacy-focused Linux user, discovered this change in April while installing a new operating system on a Ryzen 7 9700X, which is part of AMD’s Zen 5 architecture. When he utilized Host Security ID, a tool for auditing firmware and hardware security, he noticed that the encrypted RAM reported a status change from “Encrypted” to “Not supported,” without any corresponding updates to the BIOS or the system.

      Kilpatrick reported the issue on AMD’s public engineering GitHub. Two AMD engineers responded, with Tom Lendacky, a fellow software engineer, stating he did not know what caused the issue and suggested changing the BIOS setting. Mario Limonciello, a principal tech staff member and maintainer of the Linux firmware update utility fwupd, provided the same recommendation.

      Neither suggestion proved effective. Kilpatrick escalated the issue to MSI, the motherboard manufacturer, convincing their engineering team to perform controlled tests.

      The results were conclusive. MSI tested both a consumer Ryzen 9800X3D and a Pro Ryzen 9945 on the same Asus X870E motherboard, using the same BIOS. The Pro chip indicated TSME was enabled (status 1), while the consumer chip showed it was not supported (status 0).

      MSI’s BIOS team conducted further inquiries, inspecting memory captures from AMD’s Boot Loader, a part of AMD’s firmware that initializes hardware prior to OS loading. They discovered that an internal AGESA flag, DfIsTsmeEnabled, returned FALSE for the consumer processor irrespective of whether TSME was set to AUTO or ENABLED in the BIOS, whereas it returned TRUE for the Pro chip.

      Both processors share identical silicon. The limitation is enforced solely through firmware. The consumer Ryzen processor has the capability to encrypt memory but is being directed not to do so.

      When Kilpatrick relayed these discoveries to AMD’s engineers on GitHub, he directly inquired if the DfIsTsmeEnabled status being FALSE for consumer chips was due to a silicon limitation or a firmware policy. Limonciello replied: “My apologies; but I don’t have any more information to share on this topic,” and the conversation concluded there.

      AMD declined to answer questions from Ars Technica, only stating that TSME “is a security feature only applied to PRO CPUs as part of AMD PRO Technologies.” This is the first time AMD has made this restriction explicit. The company has previously stated that a related feature, Secure Memory Encryption, is exclusive to Pro and EPYC tiers, while TSME was in a more ambiguous category.

      This history complicates AMD's stance. In a 2020 GitHub discussion about encryption features on AMD processors, Lendacky confirmed that a Ryzen 3700X, which is a consumer chip, “should support TSME.” In a follow-up in 2025 in the same thread, he even recommended the use of TSME on what was evidently a consumer processor.

      Security vulnerabilities at the chip level have historically caught vendors off guard, but this instance does not reflect a newfound flaw; it involves the withdrawal of an operational feature.

      AMD never officially marketed TSME as being available on consumer Ryzen chips. Nevertheless, the feature functioned, and AMD's engineers verified its operation, allowing users to base their security measures on it.

      This change was implemented through a routine AGESA firmware update, without any release notes, advisories, or detection methods for Windows users. On Linux, detection required utilizing HSI or manually reading a specific hardware register.

      The practical consequence is clear: users of consumer Ryzen processors who depended on TSME for protection against physical access threats, including journalists, activists, security researchers, and others handling sensitive information on laptops, have lost that protection without prior notice.

      The BIOS setting for TSME remains visible and toggles, but it is ineffective.

      Detecting firmware-level security changes in processors is notoriously challenging for end users, and chip manufacturers have historically been slow to communicate them. AMD's lack of transparency regarding whether this was a deliberate policy decision or an unintended oversight makes it difficult for affected users to gauge their risk.

      Joe Fitzgerald, an expert in silicon-level security, told