3.3 volt & 5 volt EDO

Note: All 32MB and 64MB 3.3v and 5v EDO DIMMs listed on this page are high-quality 168-pin, Extended Data Out (EDO), JEDEC-standard, 64-bit-wide, 2k refresh, with an access time of 60ns. All 3.3v EDO DIMMs are unbuffered, in accordance with Apple/Motorola developer specifications. Chip-sets vary, but 2k refresh EDO DIMMs invariably work error-free in the Power Macs and Mac clones listed below. All 128MB DIMMs are 4k refresh, and work in all Power Macs listed below, with the exception of the PowerBase, the Power Mac 4400, 6400, 6500, 5400, 5500, 6360 and the TAM. The memory controllers used in all Alchemy, Gazelle, or Tanzania variants cannot handle 128MB DIMMs, requiring a pair of 64MB DIMMs to reach their maximum configurations.

Please note that 162244-compliant memory (required for NewerTech upgrades) is now available as a separate part number. If you have a NewerTech upgrade, please ensure that you order 162244-compliant DRAM. We do not, at this time, carry a 64MB DIMM which is 162244-compliant. If your Macintosh cannot accept a 128MB DIMM, and you have a NewerTech upgrade, make certain that you talk to us before ordering. Fortunately, NewerTech upgrades are the only upgrades for PCI Power Macintosh which suffer this incompatibility. Sonnet, PowerLogix and XLR8 long ago engineered around this issue, and their upgrades can accept correctly engineered DRAM with buffers besides the 162244.

It must be stressed that all PCI Power Macintosh support buffered 5v EDO memory with the exception of the Power Macintosh 4400-series, the Power Mac 7200-series, and Power Computing Power Macintosh clones.

The Power Mac 4400 requires unbuffered 3.3v EDO memory. The 7200-series Power Macintosh requires FPM DIMMs. All Power Computing clones require FPM DIMMs, with the exception of the PowerBase. The PowerBase requires 5v EDO.

The 7200 (and presumably its variants from Power Computing) can suffer motherboard damage in the event EDO is inadvertently used. Although Power Computing has stated publicly that EDO DRAM does not damage its Catalyst-based logic boards, there is no doubt that it does cause persistent system errors severe enough to render computers unusable.

MacGurus strongly recommends against the use of EDO memory in all Power Computing clones with the signal exception of the PowerBase.

MacGurus strongly recommends the use of 5v EDO in all Alchemy or Gazelle variants, specifically the Apple Power Mac 6360, 5400, 5500, 6400, and 6500. Although Apple specifications recommend the use of FPM in some of these machines, MacGurus has noted far better compatibility using 5v EDO. Just make sure you do not order DIMMs in densities higher than 64MB. The memory controller used on Alchemy logic boards cannot recognize 128MB DIMMs.

UMAX S900/S910's that shipped with NewerTech G3 daughtercards require so-called "2244" or "4244"-compliant memory. Please order 2244-compliant memory as listed above. This issue is addressed further in a footnote at the bottom of this page. It should be noted that UMAX recommends either 5v FPM or EDO memory in S900/S910 Power Macs. MacGurus has experienced best results using 5v EDO in S900/910 units.

The 3.3v EDO DIMMs on this page are specifically designed to support:

Note: Tanzania motherboards typically have three DIMM memory slots which are viewed by the memory controller as five distinct banks of memory. In practice, Slot 1 can accept only single-banked DIMMs, while Slots 2 and 3 can accept either single or double-banked DIMMs. The following configurations are typical:

  • Slot 1 : 8MB, 16MB, or 32MB DIMM (single banked)
  • Slot 2 : 8MB, 16MB, 32MB, 64MB DIMM (single or double banked)
  • Slot 3 : 8MB, 16MB, 32MB, 64MB DIMM (single or double banked)

Note: 3.3v and 5v EDO memory are not interchangeable, whether in function or in form factor. All 3.3v and 5v EDO DIMMs are physically keyed with notches in different positions along the leading edge of the DIMM. Nonetheless, it is incumbent upon the end-user to ensure that appropriate memory is utilized. MacGurus will not be held liable for end-user error. If you are in doubt about which components to install in your machine, or in your ability to successfully install them without damaging your logic board, please contact your local authorized Apple dealer. Don't void your warranty!

The 5v EDO DIMMs on this page are specifically designed to support:

Apple Technical Information Library (TIL) article Power Macintosh Computers: Using FPM, EDO, SDRAM & SGRAM notes that only the Power Mac 5500, 6500, and some variants of the Performa 6400 can fully benefit from the improved read cycles afforded by 5v EDO. In order for these Macs to benefit from EDO, however, all memory installed must be EDO. In the event FPM and EDO memory are mixed in these machines, the memory controller will address the DIMMs in Fast Paged Mode (FPM). Interestingly, MacGurus has noted far better compatibility in these Alchemy variants using 5v EDO rather than 5v FPM, and strongly recommends its use.

All other Apple Power Macintosh, with the exception of the Power Mac 7200, can utilize EDO memory, but reap no performance benefit from doing so. Apple technical documents emphasize that utilizing EDO memory in the Power Mac 7200 may damage the motherboard, and may not be covered under Apple Computer's limited hardware warranty.

Accordingly, the following Power Macintosh can accept EDO memory in either SIMM or DIMM form factors, depending upon their architecture: Power Mac 6100, 7100, 8100, 5200, 5300, 5400, 6200, 6300, 6400, 7500, 7600, 8500, 8600, 9500, 9600 and 6360. EDO SIMMs are not stocked by MacGurus, but are available as special order items. If you require EDO SIMMs, please contact a MacGurus support engineer.

1Note: Power Computing Corporation has publicly confirmed that PowerBase clones require 5v 2k refresh EDO DIMMs with an access speed of 60ns, although other logic boards based on the Alchemy specification, like the Performa 5400 & Performa 6400, also accept FPM DIMMs. In fact, PCC goes so far as to state: "The PowerBase and all Alchemy based machines require EDO DIMMs. Fast paged mode DIMMs, which are commonly used on previous machines, will not work."

2Note: While UMAX technical documents state that either FPM (Fast-Page Mode) or EDO (Extended Data Out) DRAM is compatible with the S900/910, C700 and C500, experience has shown that 5v EDO works best. The 5v EDO 2244-compatible DRAM sold on this page is compatible with all listed UMAX Power Macs, including those that require "244" or "4244" compliant memory (such as those with NewerTech G3 upgrade boards). Additional details on this particular issue may be found in the SuperMac Knowledge Base record KB00057, "Processor Card Troubleshooting Memory/DRAM DIMMs."

Model number links above point to logic board diagrams elsewhere on this website. The diagrams may be useful to experienced Macintosh users in identifying significant motherboard landmarks and memory expansion slots. If you do not see a diagram for your Macintosh and need assistance, feel free to email a MacGurus support engineer. If you are in doubt about your ability to handle sensitive electronic components, please contact your local authorized Apple dealer. Do not void your warranty!