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The GA-8SIMLNF is an OEM MOBO so you'll need to go to the OEM site for any BIOS support.
As far booting off the CD/DVD the CD/DVD media needs to be 'bootable'. If it's a Windows CD/DVD try holding F8. I assume "have tried re setting in the bios"
meant that you changed the Boot Order in the BIOS to boot off the CD/DVD as first priority and next the HDD.