The iMac G5 featured a 2.0 GHz PowerPC 970 (G5) processor, 512 MB of 400 MHz PC3200 DDR SDRAM, a 250 GB (7200 RPM) Serial ATA hard drive, a vertically-mounted slot-loading 8X DVD-R/CD-RW SuperDrive, and built-in stereo speakers at the bottom of the display. The screen was a 20-inch TFT Active Matrix LCD at 1680×1050. Wired ports included FireWire 400 and USB 2.0. Wireless connections included AirPort Extreme (802.11g) and Bluetooth 2.0+EDR.
Like its predecessors, the iMac G5 rested on an aluminum stand with an adjustable hinge. It also supported the VESA (Video Electronics Standards Association) mounting interface standard which allowed the iMac to be mounted directly on a kiosk, wall, or arm. The iMac G5 also had an Ambient Light Sensor under the edge of the display that dims the sleep indicator light when the room is dark.
Source: EveryMac.com