HPE's Mild-to-Wild Rack Tour: From ORv3 to the Cray GX5000

One thing has become clear: agentic AI is not going to run in just one type of data center. It will spread across enterprise server rooms, colocation facilities, national labs, and sovereign clouds. Each of those environments requires a different combination of compute, storage, and networking, and all of that heterogeneity has to fit into the same physical infrastructure. At the center of it is the rack.

I asked the HPE team to walk me through it at OCP Summit. Strolling from an open-standard ORv3 rack to a 400-kilowatt Cray supercomputing rack, we called it the mild-to-wild tour. My guide was Jason Zeiler, a data center infrastructure lead. Our conversation raised an interesting question about the future of AI infrastructure: Who gets to define the rack? And can one vendor support both industry-standard configurations and highly specialized systems?

Why the rack now matters more than ever

For decades, the rack was largely a standardized enclosure: you picked a width, bolted in servers, and moved on. But the power, cooling, and networking demands of AI are changing how operators approach rack design.

It’s not just about floor space either. As HPE noted in The Next Platform, the industry is now wrangling with power densities ranging from roughly 30 kilowatts to as much as 1 megawatt. While liquid cooling already extends across entire racks to manage the heat, AI infrastructure also calls for sufficient network bandwidth and reliable power delivery.

These considerations become more complicated as operators combine different hardware generations and workload types within the same facility. A rack architecture needs to accommodate not only its current equipment, but also the operational demands of future upgrades.

Rack dimensions and component placement influence how much hardware operators can deploy within a given footprint, as well as how they maintain and service those systems. The mild-to-wild tour demonstrated just how significantly these requirements vary depending on workload and deployment environment.

Mild: ORv3 and the open-standard path

Our first stop was an Open Rack Version 3 (ORv3) configuration, an OCP-standard rack with 21-inch rail-to-rail spacing. Jason described it as the next generation of scalable infrastructure, a repeatable design that uses Open Rack Unit (OU) increments and provides a consistent platform for HPE’s next-generation servers.

“Mild,” however, doesn’t mean modest. Jason was clear that HPE is planning for greater rack density.

“If customers want to fully load racks, they’re also going to have proper cooling and power,” he said.

ORv3 supports native liquid-cooling capabilities, power shelves, and multiple voltage ranges to accommodate higher-density deployments. This is a deliberate design decision to support scalability, not simply a lower-power alternative.

HPE’s new ProLiant Gen13 family reflects this flexibility, with four servers designed for two different rack standards. According to HPCwire, the DL585a and DL525 use conventional 19-inch racks, while the XD245 and XD285 support 21-inch ORv3 configurations for AI and high-performance computing (HPC) workloads. Availability is staggered: HPE expects the systems to become available in phases beginning later in 2026. This gives operators a choice between established rack infrastructure and newer OCP configurations as they plan future deployments.

HPE is also adapting HPE Juniper Networking QFX Series switches for ORv3-compliant deployments. As rack density increases, networking equipment must be considered as part of the rack’s total thermal and power budget, alongside compute.

But rack density is only part of the equation. Organizations also need the flexibility to adapt their infrastructure as workloads evolve.

When I asked Jason who this rack is really for, he described enterprise deployments ranging from half a rack to a thousand racks. Many customers aren’t building enormous, homogeneous clusters. Instead, they want to deploy different types of technology over time. That could mean mixing CPUs, GPUs, storage, and networking within a standardized rack architecture, then adding or replacing systems as workloads evolve. ORv3 provides a consistent form factor for that kind of incremental expansion.

Wild: the Cray GX5000

At the other end of the spectrum is the HPE Cray GX5000, a purpose-built supercomputing system designed for extreme compute density. And the difference in scale is staggering.

Where ORv3 uses 21-inch rail-to-rail spacing, the GX5000 uses a purpose-built 900-millimeter-wide compute rack, compared with the 21-inch equipment architecture used by ORv3. Standing beside the cabinet made its scale immediately apparent. The larger form factor accommodates substantially greater power density.

According to The Next Platform the GX5000 supports up to 400 kilowatts per rack, while liquid cooling extends to the compute blades, networking, power supplies, and even the bus bar. Rather than adding cooling capabilities to a standardized rack, HPE designed the GX5000 around a fully liquid-cooled architecture.

The increase in density is particularly striking when compared with the previous-generation Cray EX4000. Compared with the previous-generation HPE Cray Supercomputing EX4000, the GX5000 reduces the compute-rack footprint by 25%, moving from a 1,200-millimeter-wide cabinet to a 900-millimeter-wide rack while supporting up to 400 kilowatts per rack.

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