I will be happy to assist you. You are looking for the BIOS and firmware update files for the Intel® Server Board S5500BC. These files are available at https://downloadcenter.intel.com/product/36601/Intel-Server-Board-S5500BC Downloads for Intel® Server Board S5500BC
https://www.intel.com/content/www/us/en/support/server-products/000006976.html How to Update Your BIOS for Intel® Server Boards and Intel® Server Systems explains the options available.
The support available for your motherboard is limited now; Intel stopped launching new drivers and firmware versions since 2014. The link below provides with all the support available for your motherboard: https://www.intel.com/content/www/us/en/search.html?keyword=S5500BC&toplevelcategory=Support&query=S... Intel® Server Board S5500BC support