Solus Operating System is available for 64-bit (x86_64) computers, and currently comes in two main flavours. The beta2 ISO is a past release, using stable repositories. The daily ISO is updated as often as we stabilise the repositories, and as such is far more up to date than the older beta2. We recommend you use a USB stick instead of optical media, and when doing so please note that “unetbootin” is not supported, as it will not work at all.
You can install Solus on either an older BIOS-only machine, or newer UEFI devices.