AS400 Power Requirements by Model: What Buyers Should Check

The Two Numbers On This Page

There are two tables below. The first carries IBM rated maximum power, maximum thermal output and operating voltage for 39 machine types, from the 9406-270 through the Power 11 E1180. The second carries IBM measured idle and maximum draw for the models where IBM publishes it, set against that rated figure.

The first table is for the electrician: circuit size, breaker, plug and receptacle. The second is for the UPS and the room: battery capacity, runtime and cooling load. Sizing a UPS from the nameplate rating is the most common way to overspend on an install, and the gap between the two tables is where that money goes.

Rated Power and Thermal Output by Machine Type

IBM publishes a rated maximum power figure and a maximum thermal output for every machine type. Those two numbers, with the operating voltage, are what an electrician and a facilities planner need before a machine is ordered or moved.

The table covers the machine types still found in production across Power 5 through Power 11. Find the machine type on the serial tag rather than working from the marketing model name, because several models share a name across generations.

The table starts with the 9406 machine types, because a machine still labelled AS400 usually carries a 9406 serial tag. It then continues through the Power generations that replaced them.

What These Machines Actually Draw

The rated maximum is a nameplate figure. It exists so an electrician can size a circuit and a breaker with the machine fully populated and running flat out. It is not what the server pulls in normal operation, and treating it as the operating load leads to oversized UPS and cooling purchases.

IBM also publishes measured idle and measured maximum draw. On Power 9 and Power 10 the gap against the nameplate is often a factor of two to four. On Power 11 it narrows sharply: the S1112 measures 449 W against a 550 W rating, and the E1150 measures 4,643 W against 5,400 W. Newer machines run much closer to their rating, so the old habit of halving the nameplate figure no longer holds.

Reading the Table Against a Replacement Decision

The entry class is where the generational trend is sharpest. Rated draw for the entry machine climbed to 1,600 W at the Power 9 S914, then fell to 1,075 W at the Power 10 S1014 and 550 W at the Power 11 S1112. A shop replacing an S914 with an S1112 cuts rated load by roughly two thirds, keeps a standard 120 V circuit, and drops from 4U to 2U.

At the top of the range the trend runs the other way. The Power 11 E1150 is rated at 5,400 W against 4,220 W for the Power 9 E950 it replaces. More capacity in the same rack space means more load per rack unit, so a like for like enterprise refresh can need more cooling rather than less even when the workload does not change.

• Confirm the machine type from the serial tag, not the model name.
• Size the circuit and breaker from the rated maximum in the first table.
• Size UPS capacity and runtime from the measured maximum in the second table.
• Check whether the model needs 200 - 240 V only, because several entry models accept 120 V and most larger models do not.
• For enterprise models, multiply the per node figure by the node count and add the system control unit.

Check The Exact Machine Type

Do not size infrastructure from a generic Power generation label. The exact model, power supply configuration, disk layout, adapter mix, and rack plan all affect the result. A small entry server and an enterprise Power server sit in the same platform family but create very different room demands.

The facilities conversation should use the actual quote or configuration, not a blog post number copied from a different model.

What To Bring To The Electrician

The tables give a figure per machine type. Turning that figure into a work order needs the real configuration, because power supply count, adapter mix and rack plan all move the number.

These five inputs are what an electrician or facilities planner asks for. Having them ready is the difference between a quote that holds and a second site visit.

• Final machine type and model
• Processor, memory, storage, and I/O features
• Power supply count and redundancy design
• Circuit, plug, receptacle, UPS, and PDU capacity
• Rack depth, rail kit fit, floor loading, and cooling

Choose The Installation Tier Before The Quote Hardens

Once the model and room inputs are known, the next useful question is not which UPS brand to buy. It is what level of install the business needs. A basic install gets the current system running safely. A sustainable install gives the team cleaner runtime and less incident risk. A growth install leaves room for the next Power server, storage drawer, HA gear, or network refresh.

That tier choice belongs before the quote hardens, because the UPS, PDU, rack, circuit, and cooling decisions can change the real project cost.

• Basic install: correct circuit, plug, rack fit, PDU capacity, UPS capacity, and safe shutdown
• Sustainable install: tested UPS batteries, measured load, monitoring, cooling margin, labeled feeds, and documented shutdown or failover
• Growth install: reserved rack units, PDU and circuit headroom, longer runtime, separated power feeds, cooling reserve, and future server or storage allowance

UPS Runtime Is A Business Decision

UPS sizing should be tied to what the team needs to do during an outage. Some environments only need enough runtime for an orderly shutdown. Others need time for role swap, generator start, or a controlled batch stop.

The wrong question is how much UPS is standard. The right question is how long the IBM i workload must remain stable during the specific outage scenario the business is planning for.

Cooling And Clearance Are Part Of The Purchase

Older AS/400 rooms often have hidden constraints: shallow racks, weak cable management, crowded rear access, and cooling sized for a smaller historic footprint. A hardware refresh can expose those limits quickly.

Buyers should verify rack depth, rail kit fit, hot aisle access, cooling, and circuit capacity before finalizing the procurement schedule. A server purchase that waits on electrical work is a planning miss, not a shipping delay.

Frequently Asked Questions

Where do I find AS400 power requirements?

In the two tables on this page, indexed by machine type. Read the machine type off the serial tag rather than the marketing model name, because the same model name repeats across generations.

Should power and cooling be checked before ordering an IBM Power server?

Yes. Power, cooling, rack depth, and UPS runtime can all affect the installation date. Checking them before ordering prevents a finished server quote from turning into a delayed deployment.

How do I turn BTU per hour into cooling capacity?

Divide BTU per hour by 12,000 to get tons of cooling. A 9406-890 at 32,744 Btu/hr needs roughly 2.7 tons on its own, before anything else in the room is counted.

How do I choose between a basic, sustainable, and growth install?

Match it to the outage the business actually plans for. Basic covers a safe shutdown on the current system. Sustainable adds tested batteries, measured load, and monitoring. Growth reserves rack units, circuit headroom, and runtime for the next server or storage drawer.

How many watts does an AS400 draw?

It depends on the machine type. Rated maximums in this table run from 550 W on a Power 11 S1112 to 19.4 kW on a Power 5 9406-595. Measured draw is much lower than the rating: a Power 9 S914 rated at 1,600 W measures under 351 W at maximum.

Which IBM Power models run on a standard 120 V circuit?

Entry models generally accept 100 to 127 V as well as 200 to 240 V. That includes the Power 7 720, the Power 8 S812 and S814, the Power 9 S914, the Power 10 S1014 and S1022, and the Power 11 S1112. The 2-socket 4U models and every enterprise model in this table require 200 to 240 V.

Should a UPS be sized from the rated maximum or the measured draw?

Size the circuit and breaker from the rated maximum, because that is what the nameplate figure is for. Size UPS capacity and runtime from the measured maximum. Using the nameplate for UPS sizing can overspend by a factor of three.

What are the power requirements for a 9406-820?

IBM rates the 9406-820 at 100 to 127 or 200 to 240 V ac, single phase, with a maximum power requirement of 840 W and maximum thermal output of 2,867 Btu/hr.

Related Resources

• Rack-Mount UPS and PDU Bundle
• IBM Power Server Models Buyer's Guide
• AS400 Facilities Cutover Readiness Checklist
• Glossary: AS400 Power Requirements
• AS400 Power Requirements Planning Guide
• Find AS400 Power Requirements Partners
• AS/400 9406 Power Requirements by Model, full IBM detail

Sources

• IBM Power product family