What About Power Mac 7500 CPU Upgrades?

1998 – CF writes: I’ve got a few decisions to make in the next several months, and I’d like your two cents. Right now, my girlfriend and I have two Mac OS machines.

Power Mac 7500

  1. I’ve got a Power Mac 7500 (older, somewhat fickle motherboard) upgraded with a Power Computing 604e 225 MHz daughter card (stable 45 MHz bus) and 512k L2 cache (which only seems to work well with Mac OS 8.5). I also have 112 MB RAM, a 1.2 GB Quantum Fireball and a 2.1 GB Quantum Fireball, internal 4x CD-ROM, external Zip, and 2x CD burner. I also have upgraded the VRAM to 4 MB and installed a Techworks Power3D card.
  2. My girlfriend’s system is a Power Computing PowerTower with a 150 MHz 604, 128 MB RAM, 2.1 GB hard drive (unknown manufacturer), 6x CD-ROM, plus external Zip and EZFlyer. She’s still running Mac OS 8.0 because of problems with ATM and 8.5.

Needless to say, I’m the “power-user” of the two of us. She is a designer and is happy if she can work quickly enough in Photoshop and Quark. I, on the other hand, am always looking for a few extra frames per second in Unreal or a few seconds shorter rendering time in Bryce 3D.

Here is the dilemma. I desperately want to upgrade to G3. I have a few alternatives: either upgrade my 7500’s daughter card once again and donate my 604e/225 to my girlfriend, or look at getting a new machine altogether and combine the best of the two older systems for her to use. Cost is an issue, because we will be making a major move shortly and have to save some pennies for a house, etc. Long-term cost is a consideration as well. What do you think?


Mac Daniel writes: Two Mac users – the basis of a good relationship. 😉

Although you could drop $2,000 into a really hot 400 MHz G3 card, you can get 60% of that speed for 20% the money – there are a handful of 220 MHz to 233 MHz G3 cards under $400 today. (See our Guide to G3 Daughter Cards for an up-to-date listing.)

That said, I think the sweet spot for upgrades today is in the 250-300 MHz range. Under that, the performance jump between a 225 MHz 604e and a G3 at about the same clock speed is maybe 50%. Beyond that speed, you come closer to doubling performance at very reasonable ($500-800) prices.

And remember that you’re getting two upgrades for the cost of one: a G3 for your Mac and a 225 MHz 604e for her PowerTower.



HK writes: I’ve got a 7500 with a 604/146, 144 MB RAM, and a 1 MB L2 cache. I’m wondering about the value of upgrading. I’ve got minimal money. I was thinking of the 220 cards and cranking it up.

In addition, my father has a SuperMac 604e/180 and a 6100. What do you think about them? Is it even worth it for the 6100?


Mac Daniel writes: I’m a huge fan of the 7500 because it can be upgraded so far. You can get some great bargains on 200-233 MHz 604e cards – and some of the G3 cards are under US$400. Since you already have a 1 MB L2 cache, your best value may be a fast 604e card, especially if you can find one for US$150-200.

Your father’s SuperMac is a fine machine. I have a SuperMac J700/180 at home and love it. It has all the upgrade options of the 7500 – but more drive bays and more memory capacity.

As for the 6100, I recently learned that a 1 MB L2 cache can nearly double performance. This is mostly because the 6100 uses system memory for video, which is slow. By using a cache larger than the 640 KB the system sets aside for video, the whole system can run faster.

There are also some nice G3 upgrades for the 6100, although I would find it difficult to justify that much expense on such a limited design.

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