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Apple PowerPC PDS card (in Quadra 700)


I have an Apple branded PowerPC PDS card with 601/66 CPU running at 50 MHz.
The card does boot properly into PowerPC mode when selected in the Control Panel.
The computer freezes after a while of usage constantly and can be replicated very quickly, when running MacBench (not during the CPU benchmark, but the disk benchmark).
It isn't heat related, because I added an active heat sink for testing.

I wonder, if someone else had a similar experience here. Could it be the four tantalum capacitors (C5, C6, C7, C14)? Could it be caused by a bad cache chip?


Well-known member
Just to cover all the possibilities...

When you added the active heat sink, did you clean off the old heat sink grease and use new compound? The old grease was probably a lot like chalk.

Your symptoms just sound like such a good fit for heating problems.

Oh, just read more closely about the freezing happening during disk exercise but not during CPU exercise....

What does your SCSI bus look like? Are there additional items connected besides the internal hard drive? Is the internal hard drive properly terminated?

Also, the Macintosh provides termination power, so do not enable Term. Pwr. on the drive. That can cause problems sometimes if two slightly different voltage regulators get into a fight.

Finally, you aren't using a NuBus SCSI card are you? I had a Turbo601 upgrade in a Mac IIci way back when and there was some issue with SCSI Manager loading multiple times. I think the firmware in the SCSI card loaded it and the ROMs on the Turbo601 loaded it, and then things got wonky.

There was some way in one of the control panels to stop one of the two from loading it.

I don't know if they're still up, but there were a couple of great sites that supported these upgrades. You might have to use the WayBack Machine. Something like "The Unofficial Turbo601 Upgrade Site" and a similar site for the Quadra upgrades. I forget Daystar's name for that line of upgrades, which would replace "Turbo601" in the name of the site.

Ah, a little googling. You want The Unofficial PowerPro Homepage.

Wayback to Turbo601 page: https://web.archive.org/web/20040415022708/http://www.brinnoven.co.uk/turbo601/macosiss.html

There's a section called "Eccentricities, Bugs and Solutions" that has a section on SCSI Manager.

Let's see, LowendMac claims to have duplicated the PowerPro Homepage here:


But I don't see any of the sub-pages. I would try to track it down on the Wayback Machine.

Hmmm, okay here's the page on the Wayback Machine:

Wayback to Unofficial PowerPro Homepage

It looks like there might be some interesting stuff in the "Message board" section assuming it got archived.
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Thanks so much for the swift reply!
I replaced the thermal paste each time I did a test (using IPA to remove and Corsair XTM50 to apply)
My SCSI Bus just contains one single SCSI2SD v6 with active termination.
There are no Nubus cards attached - only the PPC card in the PDS slot.

I wanted to follow your temperature thought a bit more as it is so plausible. First I did only run the main tests, but this time four times in a row. The Corsair XTM50 thermal paste on the CPU Cooler with active fan at highest speed (and Aircon to 19C blowing directly into the Quadra case). No issues running through all four tests.
The CPU cooler didn't get actually hot - not even warm to be honest.

After this I ran the full test to see, if it makes any difference and freezes the system as well. Previously it froze each single time.
==> with above setting, all is working rock solid.

With that being said ... how can I get the original heatsink to be more thermally "reactive"?


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Well-known member
I didn't have overheating problems, so I don't know how effective, if at all, it is, but what I did was get a small CPU heat sink/fan combo with a thermally conductive adhesive backing and stuck it to the large flat part of the Daystar heat sink.

These heat sink/fans were used on 68040s and either the first Pentiums or maybe 80486s. I'm sure there's something like them still available.

Alternatively you could drill some little holes in the heat sink and just mount a fan with some little bolts and spacers so it blows on or away from the heat sink. If you're really fancy, I think the heat sink is thick enough to cut threads in the hole with a tap. Then you wouldn't need nuts or bolt/screw heads on the inside side of the HS.

I put the extra heat sink on my Turbo601 because I overclocked it from 66 to 96 but that's another story.

There's a thread (in TRading Post?) from a fellow selling G4 CPUs and he says he has a limited ability to machine heat sinks. If you really want to get fancy, you might look at something like that.