Beef tenderloin trimming and cooking

Definetly cut the sinew and trim off any big pieces of fat. There will be some fat still there but that okay. Clean it up before cooking.

Butter has a really low smoke point, so your experience doesn't surprise me. I think you're fine to cut off most of the fat, as long as you keep the internal temperature low you should have a tender outcome.

Thanks for the advice. I will trim the silver skin, and I will do my best not to over-cook.
But I still want to know if I need some fat to keep the tenderloin moist.
The only other time I did a tenderloin the recipe said to put butter on top of the beef and then roast it at a really high temp, and the butter started smoking and the smoke detector went off. Lucky it was a warm day, because we had to open all the windows and doors.
So that's why I want to know if I can roast w/out the fat and still have it turn out delicious.

You definitely want to remove any silverskin that might be present. I agree with Dante on the temp - pull it out of the oven at an internal temperature of 110-125º F (typically about 30-40 minutes at 400º F)- it's not a cut of meat you want to serve past medium-rare because it is so lean.

What I like to do is trimming the meat for a nice shape and sear the meat before roast it. Then you just have to be careful not over cook the meat I like to take it out if the oven at 125 degrees rare to medium rare and moist