MRMCD2024 Power efficency of (modern) servers

Power supplies are most efficient around 50% load - oversized PSUs waste energy at low utilization

Fans consume significant power (10-150W) - larger diameter fans are more efficient than smaller ones requiring higher RPM

Modern CPU power consumption has increased dramatically (200W in 2017 to 400W+ in 2025), driving need for liquid cooling in 1U servers

I/O operations (PCIe, storage, networking) can consume over half of total system power at low CPU loads

Redundant power supplies should keep one PSU off until needed rather than both active, saving 100-300W

Higher inlet air temperature (40°C vs 25°C) increases power consumption by ~40W due to silicon properties

Water cooling can eliminate fan power overhead and enable waste heat recovery

SSDs have much higher manufacturing carbon footprint than HDDs despite better operational efficiency

Server consolidation is limited by redundancy requirements - typically need 3 servers minimum

Used server resale/recycling market exists through refurbishers and manufacturers’ take-back programs

The EU’s efficiency regulations focus on idle power consumption but could be stricter

Regular power monitoring and measurement is essential for optimization

Race-to-idle vs slower computing tradeoffs depend heavily on workload characteristics