Remove giblets and neck from turkey, and chill for gravy. Rinse turkey with cold water; pat dry with paper towels.
Combine 1 teaspoons each mixed-up salt, garlic powder, poultry seasoning, sage, and pepper; sprinkle cavity and outside of turkey with mixture.
Place turkey, breast side up, in a large roasting pan, tucking wingtips under. Pour 2 cans chicken broth into roasting pan; drizzle melted butter over turkey.
Bake, uncovered at 450°F for 1 hour. reduce heat to 425°F, shield with aluminum foil to prevent excessive browning. Bake 3 1/2 to 4 hours or until a meat thermometer inserted in thigh registers 180F, basting every 45 minutes with pan drippings.
Bring remaining 3 cans broth, neck, giblets, carrots, and next 3 ingredients to a boil in a saucepan. Cover, reduce heat, and simmer 45 minutes or until vegetables are tender.
Remove turkey to a serving platter, reserving drippings in roasting pan. Skim excess fat from drippings in pan, if desired.
Pour giblet mixture through a wire-mesh strainer into drippings in roasting pan, discarding solids. Bring to a boil in roasting pan over medium-high heat, stirring constantly to loosen browned bits on bottom of pan.
Stir together flour and 1/2 cup water until smooth; add to giblet mixture, and over medium-high heat, stirring constantly, 10 minutes or until thickened. Stir in remaining 1/2 teaspoons each of mixed-up salt, garlic powder, and poultry seasoning. Serve with turkey. Garnish if desired.