The current recommended temperature for ICT equipment as described in the ASHRAE TC 9.9 guideline is
18-27 C (64.4 - 80.6°F). This is the recommended range for the dry-bulb temperature at the inlet of the servers, which is the most critical parameter for ensuring the optimal performance and reliability of the ICT equipment. The recommended range is based on the thermal specifications of the majority of the ICT equipment in the market, as well as the energy efficiency and environmental considerations of the data centre cooling systems. The recommended range is suitable for Classes A1 to A4 of the ASHRAE thermal guideline classes, which cover different types and generations of ICT equipment.
References:
1: 2021 Equipment Thermal Guidelines for Data Processing Environments - ASHRAE2, page 1, Table 2.1 3:
ASHRAE TC9.9 Data Center Power Equipment Thermal Guidelines and Best Practices4, page 10, section 2.1
5: Does your Data Center Follow ASHRAE TC 9.9 Thermal Guidelines for Data Processing Environments?6, page 1, section 1