IBM Power 5 CPU
The POWER5 processor by eServer i5 model: processors, clock speeds, what interactive CPW meant, and how to read the CPU and processor feature out of a machine still running today.
If you are looking up a Power 5 CPU, you are almost certainly holding a machine that IBM stopped supporting years ago and trying to work out what it is before you decide what to do with it. This page gives you the processor options by model, the two things about POWER5 that still affect the decision, and the commands that read the processor out of a running system.
POWER5 is where two things arrived that the platform still runs on. Simultaneous multithreading put two threads on a core for the first time in the Power line. Micro-Partitioning let a single physical processor be divided across multiple logical partitions at sub-whole-processor granularity, which is the direct ancestor of every shared processor pool configuration running on Power 10 and Power 11 today. The silicon is obsolete; the partitioning model is not.
Power 5 CPU options by model
POWER5 processor configuration by eServer i5 model
| Model | Machine type | Processors | Clock speed | Positioning |
|---|---|---|---|---|
| eServer i5 520 | 9406-520 | 1 to 2 | Up to 1.9 GHz | Entry |
| eServer i5 550 | 9406-550 | 1 to 4 | Up to 1.9 GHz | Entry / midrange |
| eServer i5 570 | 9406-570 | 1 to 16 across multiple drawers | Up to 1.9 ... 2.2 GHz | Midrange |
| eServer i5 595 | 9406-595 | Up to 64 | Up to 2.3 GHz | Enterprise |
The 570 is a multi-drawer building-block design, so its processor count depends on how many drawers are installed rather than on the model number. Confirm drawer count and the processor feature in each drawer before quoting anything.
POWER5 and the later POWER5+ refresh are not distinguished by the model name. The processor feature code is the only reliable way to tell which one is installed, which makes reading it out of the running system the first step in any Power 5 question.
Interactive CPW: the number that confuses everyone
On this generation IBM rated machines twice: total CPW for batch and general processing, and interactive CPW for 5250 green-screen work. Many i5 machines were sold with a small interactive feature relative to their total capacity, because the interactive entitlement was priced separately and expensively. That is why an i5 that looks powerful on paper could still crawl under green-screen load.
Why it matters for sizing a replacement
If your Power 5 has been slow at 5250 work for years, the constraint may have been the interactive feature, not the processor. Modern Power generations do not carry that restriction, so the replacement you need may be far smaller than the frustration suggests.
Why it matters for valuation
Two identical-looking i5 machines can carry very different interactive entitlements, and on the secondary market that entitlement was part of what the machine was worth. Confirm it rather than assuming it from the model.
How to read the CPU out of a Power 5 you still run
From IBM i or i5/OS
DSPSYSVAL QPRCFEAT returns the processor feature code. WRKHDWRSC *PRC lists the processor resources the partition can see. WRKSYSACT gives you what the machine is actually doing, which matters more than the specification when sizing a replacement.
From the HMC
Managed system properties, processor tab. On a 570, this is also where you confirm how many drawers are populated, because the model name does not tell you.
From the operating system release
A machine still on i5/OS V5R3 or V5R4 has a release ceiling that usually decides the migration question before the processor does. Check the release before you spend time on processor specifications.
From the label
The 9406 prefix marks this as System i hardware rather than the eServer p5 equivalent. When sourcing parts, the full machine type and the processor feature code together are what a supplier matches on.
Do not size a replacement by reading across processor counts. A single modern Power core does many times the work of a POWER5 processor, and the IBM i software tier is priced per core. Matching the old processor count would put you in a tier you never needed and a recurring bill you cannot easily undo.
What to do with the answer
Once you know exactly what is installed, the decision is straightforward: identify your Power 5 for the full machine profile, end of support and risk for what running this hardware now exposes, maintaining Power 5 if the answer is to keep it running a while longer, and the Power 5 to Power 6, 7, 8, 9, 10 and 11 comparison for what each generation of move actually buys. Every model is listed in the Power 5 model directory.