| Period | 1990s to mid-2000s | Mid-2000s to late 2010s | 2020s onward | Current and emerging |
|---|
| Rack density | ≈1–5 kW/rack | ≈5–15 kW/rack | ≈30–150+ kW/rack | ≈40–150+ kW/rack |
|---|
| IT load per site | ≈0.1–2 MW | ≈5–60 MW | ≈100–1000 MW | ≈20–500 MW |
|---|
| Typical PUE | ≈1.9–2.5 | ≈1.1–1.6 | ≈1.1–1.4 | ≈1.1–1.35 |
|---|
| Default cooling | Traditional air | Chilled water | Direct-to-chip liquid | Direct-to-chip liquid |
|---|
| Representative rack | Air-cooled legacy rack | Enterprise accelerator rack | Advanced liquid-cooled AI rack (NVL72-class) | Advanced liquid-cooled AI rack (NVL72-class) |
|---|
| Building | Office-adjacent room or small purpose-built facility | Standardized warehouse shell, modular pods | Multi-hall campus, dedicated substation | Modular pods, retrofit shells, rapid expansion modules |
|---|
| Rack density | ≈1–5 kW/rack | ≈5–15 kW/rack | ≈30–150+ kW/rack in AI zones | ≈40–150+ kW/rack |
|---|
| Cooling | Perimeter CRAC units, underfloor plenum | Chilled water, containment, economizers | Direct-to-chip liquid + facility water, towers or dry coolers | Direct-to-chip liquid, dry coolers, immersion in some designs |
|---|
| Power | Utility feeder, pad-mount transformer, UPS room, diesel | Dedicated substation, modular UPS, busway | 115–230 kV interconnect, MV switchgear, 2N or distributed redundancy | Leased utility capacity, on-site gas turbines or bridging power |
|---|
| Network | Copper-heavy, three-tier, leased lines to carriers | Leaf-spine Clos fabric, fiber-heavy | Scale-up interconnect + scale-out AI fabric + front-end network | High-bandwidth low-latency GPU fabric, dark fiber to carriers |
|---|
| Operations | Manual, ticket-driven, physical media | Automated, fleet-managed, software-defined | Fleet-scale automation, AI-assisted operations | Utilization-driven, multi-tenant scheduling, GPU-as-a-service |
|---|
| Networking | Three-tier core / aggregation / access, mostly copper to the server, carrier T1/T3 and early metro Ethernet | Leaf-spine Clos fabric with oversubscription tuned for mixed north-south web traffic | Non-blocking or lightly oversubscribed rail-optimized fabrics (InfiniBand or Ethernet) beside a conventional front-end network | Dedicated per-tenant fabrics or partitioned shared fabrics; dark fiber and carrier diversity |
|---|
| Software model | Dedicated physical servers per application, manual provisioning | Virtualization, then containers and orchestration; servers are cattle, not pets | Cluster schedulers, collective-communication libraries, failure-tolerant training jobs | GPU cloud control plane: reservation, scheduling, health checks, tenant isolation |
|---|
| Business model | Cost center owned by the enterprise IT department | Public cloud (rent virtual machines, storage and services) and wholesale colocation | Internal AI products plus AI cloud services sold to customers | Reserved clusters and on-demand GPU-hours sold to model builders and enterprises |
|---|
| Primary bottleneck | Floor space and cooling distribution inside an existing building | Land, power and network reach in the right metro | Grid interconnection, transformers and switchgear, and accelerator supply | GPU allocation, energized power and the speed of capital |
|---|
| Geographic logic | Next to headquarters or the business it serves | Clusters near population and carrier hubs with cheap power and tax incentives | Wherever large blocks of power can be energized soonest | Anywhere with power available quickly: retrofits, colocation, build-to-suit and remote sites |
|---|
| Environmental trade-offs | Low absolute energy, poor efficiency: much of the power went to cooling and conversion losses | Large efficiency gains (PUE fell sharply) while total consumption grew | Hundreds of MW per campus; water use, grid impacts and embodied carbon become first-order questions | Speed-to-power can mean on-site fossil generation; choices vary widely by operator |
|---|