http://www.pcgamer.com/microsoft-points-finger-at-amd-for-spectre-and-meltdown-patches-bricking-some-pcs/

Microsoft has temporarily stopped issuing Spectre and Meltdown updates to some AMD systems after users reported the patches were rendering their rigs unbootable.

Users took to Microsoft's support forums to vent their complaints. Those affected are all running older processors, such as the Athlon X2 6000+. Microsoft acknowledged the reports in a separate support page, but said AMD's documentation is ultimately to blame, rather than the patch code.