Direct-to-chip vs. immersion: a specification checklist

Technical schedule

Give every bidder the same numbers in a form they cannot reinterpret: rack loads, processor configurations, how much heat the liquid must capture, water temperatures and pressures, water chemistry, the weather you design for, and the state the system must be in at handover.

Reliability schedule

Ask each supplier to draw the system carrying full load with one component out of service, showing every pump, controller, power feed, valve, filter, and heat exchanger involved. Redundancy claims that survive that drawing are worth something.

Operations schedule

Price the years after handover, not just the equipment: maintenance, fluid testing, swapping a server, cleaning, training, spare parts, how fast someone arrives when it fails, and disposing of the fluid at the end.

Purpose and boundary of this checklist

This page is for writing a request for information and comparing compliant bids. It does not choose an architecture in the abstract; the longer comparison covers that strategic decision. Here, inclusion means a proposal answers the same workload, site, and contract schedule without replacing buyer assumptions with its preferred test conditions. A non-compliant bid can remain visible, but its exceptions should be priced and approved before technical scoring.

Issue one common load schedule

List every rack configuration, quantity, full-load heat, expected liquid capture, residual air, arrival phase, and growth case. State whether capacity means information-technology load or cooling nameplate. Give bidders one weather file and primary-water schedule. If the project has uncertain future racks, create separate base and expansion cases rather than asking for undefined future proofing.

• Exact server and accelerator configuration where known
• Rack heat and liquid capture at full computational load
• Base, peak, and expansion quantities by commissioning phase
• Residual air load and room conditions

Require a compliance matrix

Every bidder should answer each requirement with comply, exception, or not applicable, followed by a document reference. Marketing statements do not count as compliance. Ask for capacity curves, material lists, certificates, controls points, service maps, and warranty terms. The matrix exposes where one proposal includes manifolds, fluid, commissioning, or heat rejection that another leaves to the owner.

Score mandatory gates before preferences

Mandatory gates include server warranty, net thermal capacity at the duty point, required redundancy, local code treatment, physical fit, and delivery before the compute arrives. Failures here should not be averaged away by a low price. Weighted preferences can then cover energy, water, footprint, service response, expansion, and commercial terms. Publish weights before bids arrive and record the evidence behind each score.

Ask bidders to draw scope

Require a diagram from chip to outdoor heat rejection. Color every component by contractual owner and mark the measurement and acceptance point at each boundary. Direct-to-chip bids should show cold plates, manifolds, the clean loop, distribution equipment, facility water, and residual air. Immersion bids should show tanks, fluid, circulation, exchangers, facility water, lifting, and remaining air. Gaps become owner work and should enter the price.

Normalize price and operating cost

Create a total-cost workbook using the same useful life, energy price, water price, climate hours, maintenance labor, fluid replacement, spare policy, and refresh schedule. Keep supplier assumptions visible. Include the cost of floor reinforcement, pipe routes, plant upgrades, controls integration, and temporary capacity during retrofit. Apply a sensitivity range to energy, water, and utilization rather than presenting one precise forecast.

Evidence and reference checks

Request references that match architecture, scale, climate, and operating age. A pilot proves something different from a production site. Speak with the operator about commissioning defects, fluid condition, alarms, server swaps, response time, and whether capacity ratings held on the worst day. If a supplier cannot disclose a customer, ask for witnessed factory tests and anonymized operating evidence, then score the limitation explicitly.

Contract the acceptance tests

Tie payment and handover to net capacity at specified temperatures, one-failure operation, pump power, controls integration, leak response, fluid cleanliness, and operator training. State the remedy for missed capacity or delivery. Require the final materials list and software versions. A specification has decision value only when its requirements survive into the purchase order and site test.