How long do you cook an 8 lb precooked prime rib?

A pre-cooked prime rib does not need to be cooked. You simply need to reheat it, and avoid overcooking. To do this, you will need to:

1. Preheat the oven to 200F.

2. Check the internal temperature of the prime rib; the USDA recommends a minimum of 140F for precooked prime rib. If the internal temperature of the prime rib is below 140F, you should cook the meat for an additional 10 minutes per pound. Since your prime rib is already cooked, you should stop the oven process if the meat is at 120F, because it will continue cooking and reaching 140F as it rests.

3. Remove the prime rib from the oven and let it rest for 10-15 minutes before carving.