IBM Power 6 CPU
The POWER6 and POWER6+ processor by model: cores, clock speeds, software tier, why a 5 GHz chip does not beat a modern 3 GHz one, and how to read the CPU out of a Power 6 that is still running.
POWER6 holds a record IBM has never broken: at 5.0 GHz, it is the fastest-clocked processor the Power line has ever shipped. That number is also the reason Power 6 owners routinely misjudge what they have. A 4.7 GHz POWER6+ core sounds like it should beat a 3.5 GHz modern core, and it does not come close. This page covers the processor options by model, how to identify what is actually installed, and what the clock speed does and does not tell you.
POWER6 was a deliberate bet on frequency over core count: two cores per chip, two threads per core, and a clock pushed harder than anything before or since in the Power line. It added decimal floating point arithmetic in hardware, which genuinely mattered for financial and commercial workloads that had been paying for software emulation. POWER7 reversed the bet three years later, moving to four, six and eight cores per chip at lower clocks, and every generation since has followed that direction.
Power 6 CPU options by model
POWER6 and POWER6+ processor configuration by model
| Model | Machine type | Cores | Clock speed | Software tier |
|---|---|---|---|---|
| Power 520 | 8203-E4A | 1 to 4 | 4.2 GHz (POWER6), 4.7 GHz (POWER6+) | P05 / P10 |
| Power 550 | 8204-E8A | 2 to 8 | 3.5 ... 5.0 GHz (POWER6 / POWER6+) | P10 / P20 |
| Power 570 | 9117-MMA | 2 to 16 | 3.5 GHz (POWER6), 4.4 ... 5.0 GHz (POWER6+) | Varies by processor feature |
| Power 595 | 9119-FHA | 4 to 32 | Up to 4.2 GHz (POWER6+) | Varies by processor feature |
The 570 is a multi-drawer building-block design, so its core count depends on how many drawers are installed, not on the model number. Confirm the drawer count and the processor feature in each drawer before quoting a configuration.
POWER6 and POWER6+ are not distinguished in the model name on this generation. A Power 550 can be a 3.5 GHz POWER6 machine or a 5.0 GHz POWER6+ machine and carry the same 8204-E8A machine type. The processor feature code is the only reliable way to tell, which makes reading it out of the running system the first step in any Power 6 question.
Why the clock speed misleads on this generation
Two cores at 5.0 GHz with two threads each is four threads. A single modern Power core runs eight threads, carries far more cache, executes more instructions per cycle, and sits behind a memory subsystem several generations newer. Frequency stopped being a useful cross-generation comparison the moment IBM changed direction after POWER6, and comparing a POWER6+ clock against a Power 10 or Power 11 clock will lead you to keep a machine that should have been replaced.
Compare on CPW, not GHz
CPW is the only figure that reads across generations for IBM i workloads. It accounts for threads, cache, memory bandwidth and instruction throughput together, which is exactly what frequency does not.
Compare on measured utilization
Before sizing anything, take real utilization from the machine over a full month including month-end. Most Power 6 replacements are sized from the old core count and end up substantially oversized, with a software tier bill to match.
How to read the CPU out of a Power 6 you still run
From IBM i
DSPSYSVAL QPRCFEAT returns the processor feature code, which is what separates POWER6 from POWER6+ on an otherwise identical machine type. WRKHDWRSC *PRC lists processor resources the partition can see.
From AIX or VIOS
lsconf and prtconf report processor type, implementation and clock speed. The reported clock is the fastest way to confirm whether you are on a POWER6 or a POWER6+ part.
From the HMC
Managed system properties, processor tab, for installed against activated cores. On a 570, also confirm how many drawers are actually populated ... the model name tells you nothing about that.
From the operating system release
The IBM i release running on the machine constrains what is possible. On a generation this old the release ceiling usually decides the migration question before the processor does.
Every Power 6 model is far past IBM support. Processor modules can still be sourced through third-party maintenance providers and the secondary market, but pricing has nothing to do with the original list price. Get a current quote before you plan around keeping the machine running.
What to do with the answer
Once you know the exact processor, work it through the pages that price the decision: identify your Power 6 for the full machine profile, end of support and risk for what running unsupported exposes, maintaining Power 6 for the third-party option, and the Power 6 to Power 7, 8, 9, 10 and 11 comparison for what a generational move actually buys. The architecture background is on Power 6 history and architecture, and every model is listed in the Power 6 model directory.