According to Dell's [original] documentation, the X5470 doesn't fall within its stated specs:

http://www.dell.com/downloads/global/products/pedge/en/pe_t300_spec_sheet.pdf

However, according to this, it should work (will undoubtedly require a BIOS update not reflected in the original specs):

http://accessories.dell.com/sna/productdetail.aspx?c=us&l=en&s=corp&sku=311-9708

http://www.it-expertzone.com/en/spare-parts/spare-parts-for-storage/dell-poweredge-t300-server-spare-parts

http://en.community.dell.com/support-forums/servers/f/956/p/19367548/19835513.aspx

Was it succesful please ?

Hi @pelopis

PowerEdge T300 would not be able to support Xeon X5470.