Microsoft has decided to step up to the plate and offer Intel microcode patches because some OEMs just aren't doing what they should with BIOS updates. KB4090007 updates the microcode for several Intel processors, but the original Spectre/Meltdown patch has to be in place to install this update. This update must be manually installed so go to the Windows Update Catalog to get it. Microsoft's custom updates are only meant for Windows 10 version 1709 and Windows Server, version 1709 (Datacenter, Standard) users, and not for Windows 7, 8, and 8.1 machines. Microsoft's original Meltdown and Spectre patches must be already installed.