OK I have a similar server room. The difference is that it is in a basement and it is in upstate NY. We plan on using a Trane TWE AHU with a thermo expansion valve and TTP cond. unit with a 0F low ambient electronic head pressure control. We are putting the server cabinets up on blocks with sheet metal to create a plenum under them (there are two cabinets) and ducting about 50% of the air to the plenum. The rest of the air will be discharged behind the cabinets (the AHU return is in front of the cabinets). The fan will run continuously.
Does anyone think we need anything else.