Power Macintosh 6400

The Power Macintosh 6400 (also sold under variations of the name Performa 6400) is a personal computer designed, manufactured and sold by Apple Computer from August 1996 to August 1997. It is the only Macintosh mini-tower system to be branded as a Performa, and alongside the Performa 6360 was the last new Performa-branded model introduced by Apple.
The 6400 and its Performa variants were discontinued in favor of the uniformly-named Power Macintosh 6500 in August 1997.
Hardware.
Logic board: The logic board, code-named "Alchemy", is shared with the Power Macintosh 5400 all-in-one and Performa 6360 desktop models. Alchemy is generally believed to be superior to its 5200/6200 predecessors since it had a 64-bit data path to main memory.
CPU: All 6400 models use a PowerPC 603e processor that is soldered to the computer's logic board and cooled by a fanless heat-sink. Though initially considered non-upgradable, CPU upgrades did come to market that overrode the fixed CPU by use of the Level 2 cache slot.
Sound: The new "InstaTower" case features an integrated subwoofer speaker and supports SRS surround-sound. A knob on the back of the case controls the bass level of the subwoofer; this knob only works if external speakers are connected, otherwise the internal speaker provides full sound range. There are two audio output jacks, one on the front and one on the back. Headphones plugged into the front jack will disable the internal speaker and rear jack.
Expansion: There are two PCI expansion slots as well as a dedicated communications slot that supports AAUI, Ethernet and fast modem cards. The communication slot is not compatible with similar slots on other Macintosh computers. NuBus cards are not supported.
Operating system: The Performa 6400/180 and 6400/200 were shipped with System 7.5.3 Revision 2.1; this particular release was specific to these machines as there were stability problems with System 7.5.3 Release 2 on the new hardware, especially with the video card and transferring files over LocalTalk.
Models.
All Performa models shipped with SurfWatch, a product from Spyglass, Inc. that provides adult content filtering capability; content-control software was a significant issue at the time due to the recent passage of the Communications Decency Act in the United States.
Introduced August 5, 1996:
Introduced October 1, 1996: 
Introduced November 12, 1996: