D4vd  is getting cozy in a new jail cell -- he was transferred to the L.A County Men's Central Jail just before 10 PM Monday evening, TMZ has learned. The "Romantic Homicide" singer won't be able to make many friends in the clink -- a rep for the L.A. County Sheriff's Office tells us ... D4vd has been placed in segregation because he's a noteworthy inmate, which means he'll be alone with his thoughts most of the day. The Men's Central Jail has an inmate bed capacity of 5,640 inmates and houses