• RAM expandable to 132MB by installing a single 80ns or faster 72-pin 128MB SIMM
  • Accepts 1MB, 2MB, 4MB, 8MB, 16MB, 32MB, 64MB or 128MB SIMM
  • 64 MB SIMMs must be single-banked not double-banked
  • Most 128MB SIMMs should work fine in the Quadra 605. Confirmed compatible 128MB SIMMs include:
    • Micro Memory Bank 128MB 32×32 60ns EDO non-parity 5v 72-pin SIMM EDO-D3232-60BA
    • Micron 128MB 60ns 16c 16×4 1Rx4 EDO 5v 72-pin SIMM 128T16E164-60KO
    • MemoryTen 128MB Apple Performa 630 Series 72-pin SIMM APL72P128
    • Samsung 128MB 32×36 60ns ECC 72-pin SIMM KMM53632000AK-6U
    • HP NetServer LX Pro 128MB Memory Module HPD4893A
    • Crucial 128 MB 60ns non-parity 3.3v EDO-RAM 72-pin SIMM CT32M32E4L6.M16TG
  • There are field reports of successful installation of 260MB of RAM in a Quadra 605 by using two 128MB SIMMs in a SIMM Doubler, however it is unlikely there is enough room to close the lid with this configuration
  • Note that cold boot times will be significantly longer with larger amounts of RAM due to the automatic memory test at system startup (approximately 50-55 seconds before video initializes with a 128MB SIMM installed). There is no way to bypass this memory test on the Quadra 605.


  • 68040 Upgrade
    • The stock 68LC040 25 MHz processor can be swapped with a 25 MHz or faster full 68040
    • The 68040 has a built-in FPU making some applications run significantly faster
    • You can usually find 68040 CPUs available for sale on eBay
    • There are field reports of successful installation of the Sonnet Technologies QuadDoubler 50/100 in a Quadra 605 however there is not enough room to close the lid
    • See how a QuadDoubler was made to fit in an LC 475 case here (the LC 475 is identical to the Quadra 605 with a different case)
  • PowerPC Upgrade


  • The stock MC680LC40 or full MC68040 can be overclocked to 33 MHz by moving two small resistors on the underside of the motherboard
  • This modification results in a 31% increase in CPU clock speed and 42% increase in graphics speed with no stability issues
  • Benchmark results here
  • No additional parts are needed, however a little careful soldering is required
  • A guide to perform this simple upgrade is available here
  • Photograph of the resistors that need to be moved for the 33 MHz overclock is available here
  • As a precaution, a low-profile heat sink on the CPU is recommended after performing this upgrade
  • Overclocking a Quadra 605 to 40 MHz is possible, however:


  • The MicroMac 128KB Quadra Cache Card reportedly improves performance up to 125%
  • To install you first remove the CPU, install the Cache card in the CPU socket then install the CPU in the Cache card



  • The Quadra 605 shipped with two 68-pin 256 KB VRAM SIMMs for a total of 512 KB of VRAM
  • Standard 512 KB VRAM supports 8-bit color for 256 colors at resolutions up to 832×624 and 16 colors at resolutions up to 1152×870
  • Upgrading to 1 MB VRAM provides 16-bit color for thousands of colors at resolutions up to 832×624 and 256 colors at resolutions up to 1152×870
  • You can upgrade to 1 MB by replacing the 256 KB VRAM SIMMs with two 512 KB 68-pin 80ns VRAM SIMMs
  • VRAM Expansion Kit (two kits required for expansion to 1MB VRAM) is Apple part number M0517LL/A. Available for sale here


  • Any standard height 3.5″ 50-pin SCSI hard drive should be compatible with the Quadra 605
  • A SCSI-to-SD Card adapter such as BlueSCSI can be installed for a fast and completely silent solution
  • Further discussion of SCSI hard disk replacement options available on the 68kMLA Wiki


  • Installing a 150 ohm 1/4 watt resistor on the positive (red) lead of the case fan will slow the speed of the fan. This will result in considerably less noise while maintaining sufficient cooling


  • Retr0bright – a simple treatment with hydrogen peroxide will remove any yellowing from plastic parts of the case


Quadra 605Quadra 605 motherboard

Contact Us