Idle GPUs, turned into contracted revenue.

Most AI hardware runs well below capacity for much of its life. We turn that idle time into revenue: Castellan brings contracted compute buyers to owners of GPU systems, places workloads and runs the commercial side — contracts, billing and settlement. Your utilisation rises, and the hardware stays yours. This is the owner's side of the marketplace that supplies our AI Compute customers.

Four ways to put idle hardware to work.

AI demand is looking for capacity — but idle GPU-hours only become revenue once someone turns them into a contractable product: specified, matched with a buyer, billed and reported. We handle that conversion, backed by a network of contracted compute buyers.

Spare GPU-hours

Capacity your own workloads do not use — sold per GPU-hour or in agreed time windows, while you keep ownership and priority access.

Committed capacity blocks

Whole servers or clusters contracted to one buyer for a fixed term — revenue you can plan with.

Systems in HPC Hosting

Hardware you host with us in HPC Hosting can be enrolled directly, without moving a rack.

Hardware you no longer need

When you retire or refresh a cluster, our trading desk sells the systems on — inspected and documented.

From assessment to settled revenue.

Hardware assessment

Technical and commercial review — systems, interconnect, facility, power, jurisdiction — and a realistic monetization case.

Demand matching

Your capacity matched with contracted buyers — AI labs, AI companies and regulated enterprises, including our AI Compute customers.

Offtake structuring

Contracts with defined terms and SLAs — with take-or-pay elements and indexed pricing where they fit.

Workload routing

Training and inference placed across the network to raise the utilisation of your systems.

Billing & settlement

Invoicing, settlement, SLA management and reporting — run by us, transparent to you.

Upgrade path

When you refresh, we sell the outgoing systems and source the next generation through GPU Procurement & Trading.

For owners of GPU hardware with spare capacity.

We work with AI companies and enterprises whose GPU clusters are not fully used, GPU-cloud and hosting operators with unsold capacity, and funds and other owners of GPU hardware. Systems you host with Castellan can be enrolled directly from HPC Hosting.

Hardware

NVIDIA HGX servers · GPU clusters · NVL72-class racks

Commercial models

Revenue share · fixed lease · hybrid structures

Contract tenor

12 months to multi-year offtake

Reporting

Transparent · auditable settlement

Jurisdictions

Switzerland · Europe · North America

Own GPUs that sit idle?

Tell us what you own — systems, quantity, location and current utilisation. We assess the hardware and come back with a monetization case and a commercial structure.