I'm trying to make sure I'm up to date with my Boot CD. First I created a CD from the iso folder using bootcd_x64. When I checked it with the Check Recovery Disk utility it said it was not a bootable disk. Then I created one with the bootcd image and that one checked okay. I then upgraded the version to 10.1.21.334 and downloaded the BMB Utility and created a boot disk. The Check Recovery Disk utility said that one was not bootable. I just want to make sure that I have a current bootable disk should I need to do a recovery. My primary recovery images are on an external drive connected by a USB 3.0 connection.
To check the boot CD, just try to boot with it. This will check not only that the disc is bootable, but also that it has the drivers for your hardware. The disc built from the x64 ISO should boot UEFI systems in UEFI mode.