"CPU machine check error" randomly on CPU1 or 2 about once a week, at random time. The server restarts without Windows logging. BIOS / Fireware / drivers are all up-to-date., CPU Uncorrectable Machine Check Exception (Processor 2, APIC ID 0x00000040, Bank 0x00000006, Status 0xBB800000'00000E0B, Address 0x00000000'00000000, Misc 0x00000000'AE000000). In this case unable server is not responding, even the console on iLO doesn't work and only reboot helps., That’s normally a CPU error - either a firmware bug or a sign of a failing CPU/motherboard. If a reboot cleared it then I suspect you should be looking to upgrade your systems firmware., A machine check exception (MCE) is a type of computer error that occurs when a problem involving the computer's hardware is detected. With most mass-market personal computers, an MCE indicates faulty or misconfigured hardware., A fatal Machine Check Exception has occurred. x86 Processors. If the processor has ONLY MCE feature available (For example Intel. Pentium), the parameters are: 1 - Low 32 bits of P5_MC_TYPE MSR. 2 - Address of MCA_EXCEPTION structure. 3 - High 32 bits of P5_MC_ADDR MSR. 4 - Low 32 bits of P5_MC_ADDR MSR., When hardware encounters a critical/fatal error, a machine check exception (MCE) is raised. As the machine check exceptions are considered fatal and unrecoverable, ESXi Server is expected to crash with a PSOD. This MCE is classified as an 'SRAR' (System Reset Assert Register) which means it is uncorrectable, recoverable, action required..