Law enforcement sources tell us Clyde Amerson -- known as Ace on the 2003 reality show -- was arrested and booked Wednesday morning for DUI in Carrollton, Georgia after allegedly rear-ending someone on the road.

Cops say they responded to the accident -- in which nobody was injured -- and felt Ace was under the influence since he appeared drowsy, slurred his speech and had trouble with his balance. Our law enforcement sources say he admitted taking Benadryl and Rx pills.

We're told police drew blood, and toxicology tests are pending.

Ace was taken into custody and charged with 2 misdemeanors -- 1 count of DUI and 1 count of following too closely.