PowerLogix 1.1GHz 750GX ZIF, afraid of chipping the die

[cobalt60]

I was lucky enough to find one of these, but have been too afraid to install a heatsink to it due to reading reviews of people chipping the die, even after bending the heatsink clip to make it apply less pressure. To make things worse, mine does not have any sort of like strain relief or leveling pad or whatever it is that is on basically every other G3 ZIF, so not sure if it was removed from this unit, or these simply didn't come with them.

Main thing im looking for is suggestions on what I could use as a leveling pad. Ive tried removing them from some dead modules I have, but the sticky tape or whatever it is stays attached to the ZIF and doesn't come off with the pad. Im afraid using double sided tape may be too thick. Also not sure I should assume the 750GX die is the same exact height as the 750s; the pads have very little give to them if not. But then, if I do happen to not make good contact with the die, do I risk damage from that, due to overheating?

 

[herd]

I don't know of any foolproof off-the-shelf solution. What does the manual have to say?

If it were me, I'd measure things and fabricate/modify as needed. I have previously used pieces of plastic glued to the corners of the CPU substrate with RTV for this purpose. I think I found an old credit card that had the needed thickness. I would also check that the fulcrum of the spring clip lines up with the die and has a clearance that is only slightly less than the thickness of the metal that will fill the gap. If you do a mock-up assembly with the parts clean and dry, you can hold the die against the heatsink with light finger pressure and hold it up against a light and see where contact is (or is not).

I think that CPU is pretty low power, so I don't think it will instantly self destruct if the cooling isn't perfect.

 

[macuserman]

They do have a very small die, and you have to be very careful with it. That is a good find! I had to look quite hard for mine. I have a 1Ghz and a 1.1Ghz, that I may have damaged....

 

[cobalt60]

mock-up assembly with the parts clean and dry, you can hold the die against the heatsink with light finger pressure and hold it up against a light and see where contact is (or is not)

awesome idea, thank you

I have a 1Ghz and a 1.1Ghz, that I may have damaged....

I hope you mean only the latter is damaged. How did you maybe damage it?

Any thoughts on using one of those graphite thermal sheets instead of thermal compound? Not sure if they get thinner, but 0.2mm is readily available. It would increase the pressure on the die, but would keep aluminum from hitting the edges of the die.

In the meantime, I was hoping to find some more elegant solution, but I think I'm just going to make the leveling pad out of layers of kapton tape.

 

[cobalt60]

Does anyone know if the 750GX has temperature sensors, and if so, are they readable from OS 9, OS X, or Linux?

 

[Phipli]

Does anyone know if the 750GX has temperature sensors, and if so, are they readable from OS 9, OS X, or Linux?

I think they all thave a temperature sensor in that G3/G4 era.

Not sure if I've tried a GX specifically, but in OS9, generally Newer's Gauge Pro generally does a good job of reading temps. Mostly.

 

[cobalt60]

Neat. I noticed it had a temp reading but always dismissed it as inaccurate. First off, still on the 520MHz 750L. It normally says 71F (22C), which is like exactly room temperature, so I sorta dismissed it as not accurate. But actually these G3s are so low power I can believe that's not far off. After a brief "stress" test, I got it up to 78F (26C). I noticed that is the only 2 temperatures it will show, so, I guess it's quite a low resolution, at least with my CPU.

I plan on doing some weird things with the GX, like possibly adding thermal grease when the heatsink already has a (super slim) pad, all in the hopes of not cracking the die. Definitely want to monitor temps for this.

Edit: actually just saw a 73F briefly