can't install os on new built computer

[LetsEatCrayons]

So.I just got done building my new pc and it boots to bios and eveything seems to work but when I try to boot from usb to install my os it tells me to insert proper boot media. It has the Iso file on it and I have it as the boot priority and force boot it too. The motherboard is set to uefi and legacy. I even went up to microsoft and had them out a win7 iso on a usb. I have keys for both win8 pro and win7 home.
Just at the final stage of making my system install Windows.

I5 processor
Msi z97 gaming motherboard
16 gb ram
Antec power supply
Samsung 500gb ssd
Nvidia 970 graphics card

 

[popatim]

Try either disabling secure boot int he bios
or
During Post, when you are prompted to enter the bios, press the key that corresponds to select boot device and then chose the usb from that list