What Can I Do with a Quadra or Centris 650?

1998 – Mac Daniel will be enjoying the Christmas holiday with family. The next column will appear on December 28.

Why Is There No PDS G3 Upgrade for the Quadra 650?

Quadra 650MKT writes: I have been a fan of your Low End Mac site and find the information you provide very helpful. I really appreciate what you are doing for Mac users. Thanks for the good work.

Anyway, I have several Macs at home and lots of plans for them. My first question is about my beloved Quadra 650 with an upgraded 1.2 gig Quantum/Apple hard drive and 32 MB RAM. The prescribed upgrade path for this machine is to upgrade it to a 7100 or PowerPC upgrade before I can upgrade it to a G3 card.

Why is it not possible to purchase a G3 card designed for the PDS slot and plug it into my machine? Is the bus not fast enough? The machine has a 33 MHz 68040 with a 66 MHz bus, right?

Also, is the instruction for upgrading a 128K Mac available anywhere? I have adopted a 128K, and it’s in great shape. What can I do?

Thanks in advance for any information you can give me.


Mac Daniel writes: The Quadra 650 uses a 33 MHz 68040 processor. One nice feature of the 68040 is that it runs internally at twice the speed of the system bus – in this case, the heart of the CPU beats at 66 MHz while the bus itself is only 33 MHz.

Apple did make a PowerPC upgrade for the Quadra series, but it only ran at double bus speed. On your Q650, it would become a 66 MHz Power Mac. But those cards are long discontinued and difficult to find.

The other option is to replace the motherboard with a 7100 motherboard. This gives you a full Power Mac at either 66 MHz or 80 MHz – neither speed is earth shaking these days.

With the PowerPC upgrade card, there was no way to take it a step further and install a G3. With the 7100, there are G3 upgrades.

However, by the time you pay for a 7100 board and a G3 upgrade, you’re almost in the price range of an iMac. The best prices I’ve seen for the logic board and G3 card adds up to about US$900. For about the same price you could keep your Q650, buy a nice used 7500 (US$550 and up), and add a 220 MHz or 233 MHz G3 card.

Or sell the Quadra and invest that in an even faster G3 card.

Original Macintosh

Upgrades for the original Macintosh are hard to come by. I recommend leaving it alone and trying to find the 512K, 512Ke, or Plus you want to upgrade it to. Used 68000-based Macs are so inexpensive right now, it’s almost always cheaper to buy a used one than repair or upgrade what you already own.

Looking for Advice on a Larger Hard Drive & More Memory

FK writes: I have a Centris 650 16/230. I know I need a larger hard drive. I also have a IIci 12/80. I could trade both or get more memory and a hard drive for the 650. I also have a 4x portable CD-ROM.


Mac Daniel writes: You can pick up a 1.2 GB Apple drive for $99 from MacResQ, to name one ad that is popping up all over the Internet these days. (I’m sure other dealers have similar deals as well.) And memory is not unreasonable these days – ramseeker shows 32 MB 72-pin SIMMs for your Quadra for as little as $45 each. So for about $200 you can pretty nicely max out your Centris 650, maybe without even selling the IIci.

The iMac has not been kind to the used Mac market, except from the buyer’s perspective. Not too long ago I purchased a Quadra 650 24/250 for $150 plus shipping; your Centris would be worth a bit less, maybe $125. The IIci has dropped below the $100 mark.

It’s not that these computers have lost any real value as working machines – this is only relative to the incredible value of the iMac

If you’re satisfied with the performance of your 650, get the hard drive and memory. The value of your low-end Macs can’t go down much further, so you have little to lose by holding on to them longer.

On the other hand, if you need more horsepower, the $250 or so you’ll get for your older Macs won’t go far in buying a Power Mac.

On the gripping hand, expect new Power Macs in January, which will drive down prices of first- and second-generation Power Macs on the used market, perhaps putting them comfortably within your grasp.

Reader Feedback

RT writes: In addition to getting another, larger hard drive for the Centris, I believe FK could also move the Centris’ 230 internal hard drive to the IIci, giving him a IIci 12/230.

Keywords: #quadra650 #centris650

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