How to boot from a flash drive on a Mac Pro 2008?

I bought a Mac Pro 2008. Was on El Capitan drive.

Decided to put too El Capital but only on the SSD. Made a bootable USB flash drive. Checked out on the beech: is downloaded and ready to install. Put in the Mac Pro, hold Option appears on the boot menu. Choose the flash drive. And she is ignored and loaded hard.

How to fix the situation?
March 23rd 20 at 19:13
1 answer
March 23rd 20 at 19:15
I get to start installing external loaders type Clover EFI.

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