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You are here: MacNN Forums > Enthusiast Zone > Hardware Hacking > How hot is too hot?

How hot is too hot?
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bojangles
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Jan 2, 2003, 12:17 AM
 
I tried to swap out the mobo on my beige G3/266 today�just got a Rev.B on eBay; had a Rev.A�and it didn�t take. Don�t know why. Whatever the case, I put the original mobo back in and am getting much higher temperature readings. Whereas I used to get cold-boot temps of 28˚C and intense-usage temps of 32˚C, I�m now booting at 36-40˚C and watching it climb to a steady 56˚C with normal usage.

What gives? The heat sink seems to be situated correctly. It�s warm, so I don�t think the temp is reading incorrectly.

For that matter, how hot is too hot?

Please help!
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bojangles  (op)
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Jan 2, 2003, 12:18 AM
 
Right after I posted that, it climbed to 60˚C. The computer�s been on for about 20 minutes.

Shutting down now.
“The trouble with quotes on the Internet is that you can never tell if they’re attributed to the right person.”
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Evinyatar
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Jan 2, 2003, 07:22 AM
 
Try cleaning off the heat conducting stuff of both the CPU and the heatsink and replacing it with a fresh layer.
     
bojangles  (op)
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Jan 2, 2003, 07:42 AM
 
Sorry, I�m new at this kind of thing. I assume you mean the little black square on the bottom of the heat sink? (I don�t see anything on top of either that CPU or that of my other [non-functioning] G3.)

On a related note, what�s this �heat-conducting stuff� called (so I know what to ask for), and any ideas where I can get it?

Thanks!
-
32˚C after being off for seven hours
40˚C after being on for ten minutes.
“The trouble with quotes on the Internet is that you can never tell if they’re attributed to the right person.”
—Abraham Lincoln
     
Spliffdaddy
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Jan 2, 2003, 11:27 AM
 
It's called "thermal grease (paste)" or "heatsink compound" and it's available from Radio Shack. I think it's $1.99 for a small tube.

Just spread a thin layer of the 'thermal grease' on top of the CPU where it mates with the bottom of the heatsink.

It helps transfer the heat from the CPU to the heatsink. Air is a poor thermal conductor - and that's pretty much all that's between the mating surfaces of the CPU and heatsink, unless you use thermal grease.


Clean off the old stick-on 'thermal pad' if it's still attached - before you spread the thermal grease.

PS,

"Too hot" is any temp over 150F

Heck, even 200F won't damage the CPU - but it prolly won't be interested in working at those temps, either.
( Last edited by Spliffdaddy; Jan 2, 2003 at 11:35 AM. )
     
bojangles  (op)
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Jan 2, 2003, 01:35 PM
 
Thanks, Spliffdaddy. I�ll stop by Radio Shack on the way home. Guess they�re good for something, after all.
“The trouble with quotes on the Internet is that you can never tell if they’re attributed to the right person.”
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bojangles  (op)
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Jan 3, 2003, 08:59 AM
 
I picked up some �heat sink compound� at Radio Shack yesterday, but I�m still kind of worried. My wife says the G3 was running at 40-44�C all day yesterday, and after applying the heat sink compound, it�s exactly the same: 40-44�C. Here�s my steps:

1) Detached the computer�s power cord and opened him up.
2) Removed the heat sink.
3) Squeezed some compound out of the tube, directly onto the processor.
4) Reseated the heat sink.
5) Closed him back up, reattached the power cord, and booted back up.

Did I do something wrong?
“The trouble with quotes on the Internet is that you can never tell if they’re attributed to the right person.”
—Abraham Lincoln
     
php
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Location: Bridgeport, Connecticut, USA
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Jan 5, 2003, 03:33 AM
 
This probably qualifies as being too hot:

http://www.theregister.co.uk/content/54/28245.html
     
bojangles  (op)
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Jan 6, 2003, 11:19 AM
 
php - That is definitely too hot.

As for Mr. BoJangles (my G3), I moved the heat sink over a bit (the compound now makes it and the processor stick together) and he�s back down to a cool 24-32�C (depending on recent usage).

Thanks to everyone who helped!
“The trouble with quotes on the Internet is that you can never tell if they’re attributed to the right person.”
—Abraham Lincoln
     
   
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