Perforated tiles on a raised floor often deliver substantially more or less airflow than expected, resulting in inefficiencies and even equipment failure due to inadequate cooling. In this paper, the impact of data center design parameters on perforated tile airflow is quantified and methods of improving the uniformity are discussed. This paper was written jointly by APC and IBM for the ASME InterPACK2005 Conference, held July 17-22 in San Francisco, California, USA. It is taken directly from the conference proceedings in its original form.