What is a 1U Server?: rawcompute.in Glossary

A 1U server is a rack-mountable computer system that fits within a single rack unit. 1.75 inches (44.45 mm) of vertical space in a standard 19-inch equipment rack. This compact form factor maximises the number of servers per rack, making 1U systems the most popular choice for web hosting, virtualisation, storage, and general-purpose compute workloads. A standard 42U rack can accommodate up to 42 individual 1U servers.

Due to height constraints, 1U servers typically support one or two CPUs, limited PCIe expansion (usually 2-3 slots with low-profile riser cards), and 4-10 front-accessible drive bays for 2.5-inch SSDs or NVMe drives. Cooling in 1U chassis relies on high-RPM 40mm fans, which can be louder than the larger fans used in 2U or 4U systems. Power supplies are typically 1+1 redundant, ranging from 550W to 1200W. Popular 1U server platforms include the Supermicro SYS-1029U, Dell PowerEdge R660, and HPE ProLiant DL360.

Why it matters when buying hardware

Choose a 1U server when rack space is at a premium or when your workload does not require multiple GPUs or extensive storage. 1U servers are ideal for CPU-centric workloads like web serving, databases, and Kubernetes worker nodes. They are generally not suitable for multi-GPU AI workloads since most 1U chassis cannot accommodate full-height, full-length GPU cards. If you need GPU acceleration in a 1U form factor, look for specialised 1U GPU servers that support low-profile GPUs or single full-height GPU via riser.