Intel investigating issue with Broadwell and Haswell processors. Customers reported higher system reboot rates when they installed firmware updates. Intel started rolling out microcode updates to fix the Spectre flaw yesterday. AMD also announced it will start shipping updates that mitigate the same Spectre flaw. Windows updates meant to mitigate the flaws caused BSOD errors earlier this week. Microsoft paused the rollout of these updates to investigate the issue. AMD said only AMD Opteron, Athlon and AMD Turion X2 Ultra families were affected.
Source: https://www.bleepingcomputer.com/news/hardware/intel-broadwell-and-haswell-cpus-experiencing-reboots-after-firmware-updates/