Obtaining CPU information in AIX

To obtain CPU information use the AIX command prtconf: 

# prtconf
System Model: IBM,9116-561
Machine Serial Number: XXXXXX
Processor Type: PowerPC_POWER5
Number Of Processors: 8
Processor Clock Speed: 1499 MHz
CPU Type: 64-bit
Kernel Type: 64-bit
LPAR Info: 2 node2
Memory Size: 31872 MB
Good Memory Size: 31872 MB
Platform Firmware level: Not Available
Firmware Version: IBM,SF240_338
Console Login: enable
Auto Restart: true
Full Core: false

Network Information
        Host Name: node2
        IP Address: 192.168.1.91
        Sub Netmask: 255.255.255.192
        Gateway: 192.168.1.73
        Name Server: 192.168.1.73
        Domain Name: example.com

Paging Space Information
        Total Paging Space: 24192MB
        Percent Used: 1%

Volume Groups Information
==============================================================================
rootvg:
PV_NAME           PV STATE          TOTAL PPs   FREE PPs    FREE DISTRIBUTION
hdisk0            active            546         82          00..00..00..00..82
hdisk1            active            546         98          06..00..00..00..92
==============================================================================
...

The ouptut contains much information about the CPU type (PowerPC_POWER5), number of CPU's (8), CPU speed (1,5GHz) etc.

The prtconf command also gives much information like Memory Size, Firmware, Server Type, Serial Number, Operating System release etc. prtconf for AIX is worth to keep in mind.
At the end you get a list with all peripherals, but I dropped that list here.