Jupie2008, how big is the drive you flashed the image to? I had to use at least a 16GB, 8GB would no longer work after the updates that were released a few days ago.

Also in your bios look for boot options. I found this on bio stars website: http://www.biostar.com.tw/app/en/support/faq_content.php?S_ID=709

Setting that should make it boot from USB.  I also had to change my pcie version to gen 1.