New to me G4 MDD. What CPU temps are normal?

crewkid89

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Original poster
Jun 16, 2011
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United States
I recently rescued a G4 MDD from going to the recycler at work. I couldn't have lucked out more. It is a 1.42Ghz DP with the Radeon 9700 Pro.

My only concern is the volume of the fans and the temperature. I know these machines have earned the nickname G4 "Windtunnel" but I just want to make sure I'm not going to burn it out. When I started it up and started using it, I was getting about 58C while web browsing. That seemed a little warm while essentially idle. I opened it up, cleaned out several years of dust and removed the large HDD bay in front of the fan holding two extra drives I don't really need. This saved me a whopping 2C bringing me to an average of 56C.

Should I be looking at replacing the Thermal Paste? I have never done that on a Mac and the idea of it is a little intimidating on a non-modern, non-ATX motherboard.

Thanks!
 
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redheeler

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Oct 17, 2014
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Very nice, the Radeon 9700 is a rare bonus!

Replacing the thermal paste is a good idea, as the old paste tends to dry out over time. Luckily taking the heatsink off is not that hard. I need to repaste my DP 1.42 as well.
 

eyoungren

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Aug 31, 2011
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I recently rescued a G4 MDD from going to the recycler at work. I couldn't have lucked out more. It is a 1.42Ghz DP with the Radeon 9700 Pro.

My only concern is the volume of the fans and the temperature. I know these machines have earned the nickname G4 "Windtunnel" but I just want to make sure I'm not going to burn it out. When I started it up and started using it, I was getting about 58C while web browsing. That seemed a little warm while essentially idle. I opened it up, cleaned out several years of dust and removed the large HDD bay in front of the fan holding two extra drives I don't really need. This saved me a whopping 2C bringing me to an average of 56C.

Should I be looking at replacing the Thermal Paste? I have never done that on a Mac and the idea of it is a little intimidating on a non-modern, non-ATX motherboard.

Thanks!
That's actually fairly normal. 56C comes out to around 132º F which is solidly in the normal operating range (usually about 125º to 148º).

Note that doing anything CPU intensive (and browsing the internet will be CPU intensive on a G4 if the browser is not optimized) will cause a spike in heat.

Macs are designed to protect themselves by executing a thermal shutdown whenever a certain heat threshhold is reached. That threshhold is several degrees before the point where any damage would occur. So, the fact that your Mac is still functional and operating means you aren't damaging it.

You'll know a thermal shutdown when you see one. One moment you'll be doing something and the next the Mac will be off - like someone pulled the power plug. It just switches off.
 

d-oost

macrumors 6502a
Jan 10, 2016
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Modern computers are designed to protect themselves by executing a thermal shutdown whenever a certain heat threshhold is reached.
FTFY ;) Nearly any computer that is a Pentium 4 or older, or a Mac of similar age, has overheat protection and will kill the power if it's getting too hot. I know early Pentium and AMD chips cooked or even exploded without a heatsink (there's a very famous Tom's Hardware video from way back when showing this), but we've come far from those days. Still, doesn't mean Apple wasn't there first ;)

Be sure to check out the PSU fan mod. It shows how to replace the two small noisy PSU fans (these are the loudest in the MDD) with one big, silent fan, while maintaining (and even slightly improving) stable temperatures. I'm going to do this some day on my 1GHz SP MDD, as the PSU is really annoyingly loud. The other fans are quite silent compared to the two PSU fans, I can tell you that!
 

eyoungren

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Aug 31, 2011
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FTFY ;) Nearly any computer that is a Pentium 4 or older, or a Mac of similar age, has overheat protection and will kill the power if it's getting too hot. I know early Pentium and AMD chips cooked or even exploded without a heatsink (there's a very famous Tom's Hardware video from way back when showing this), but we've come far from those days. Still, doesn't mean Apple wasn't there first ;)

Be sure to check out the PSU fan mod. It shows how to replace the two small noisy PSU fans (these are the loudest in the MDD) with one big, silent fan, while maintaining (and even slightly improving) stable temperatures. I'm going to do this some day on my 1GHz SP MDD, as the PSU is really annoyingly loud. The other fans are quite silent compared to the two PSU fans, I can tell you that!
How far back are we defining modern computers?

I know for a fact that my wife's 12" PowerBook has thermal protection. It shut down more than once on me when I didn't put the heatsink back before closing it up and using it.
 

d-oost

macrumors 6502a
Jan 10, 2016
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Athlon 64/Pentium 4-era computers, which kind of were the grandfathers of our modern computers. Those CPUs were IIRC the first to have on-die thermal protection. There were probably motherboard before that could go into thermal protection by themselves, but since those two lines of CPUs it's been standard for the CPU to cut it off when it gets too hot to protect itself.
 

crewkid89

macrumors regular
Original poster
Jun 16, 2011
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United States
Thanks for the advice everyone. Good to know I'm in normal operating temperatures. The 120mm fan mod with the custom duct work was pretty impressive. I don't know if I'd go that far to reduce the noise. Right now it's about 60db right next to the tower and 50 where I'm sitting. While that's definitely audible, it really isn't that big of a deal. I stopped noticing it as much as soon as I put some music on.

I'm shocked at how well it performs compared to my 1.67Ghz Powerbook. I can play Halo on pretty much high settings with hardly any lag, I can watch standard def youtube with no frame drops. When I tried both of those things on my Powerbook I pretty much got a slide show. The 9700 pro is no slouch.

Edit: I realized I forgot to mention it also came with the 17" Studio display. It's an awesome screen.
 
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jbarley

macrumors 68040
Jul 1, 2006
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I have 2 MDD's 1.42Ghz units and I've got them both running cool and near silent with different mods in each, but there is one thing both use and it drops the temperatures and noise significantly and that is "Chud Tools" ver 3.5.2.
This enables NAP mode and judging from the bench test runs I've made does not impair the operation enough to measure.
Idle and low usage 31-35C
low.JPG


After prolonged usage, web browsing, YouTube viewing and whatever, 50-58C, never much more.
Believe me, it is possible to have a quiet MDD which then becomes a real joy to use.
high.JPG
 
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for this

macrumors 6502
Nov 18, 2014
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I think you can check the upper limit of your CPU with Temperature Monitor. After the application is launched, choose Window > Show Overview, then you will see it in the Specified Upper Limit section. My 867MHz dual is listed as 62.0C.

I would still replace the thermal paste, which is quite easy by the way. Should help lower the temperature further. Here is the service manual, in case you need it: http://tim.id.au/laptops/apple/powermac/pmg4_mir_fw800.pdf
 

oi!

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Jan 10, 2016
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You lucky swine!!!

A good quality thermal past, applied by someone who knows how to do it (there's vids on YouTube) is rarely a bad idea.

I personally would also recommend 2 fans at the back of the case, I have a pair of Fractal Design Silent Series R3's, they bring CPU temps down by around 10°C and fit between the (non-copper) heat sink and the metal inner case mesh very nicely.
You can also mount larger fans to the outside of the case if you wish, better ducting around the vertical mounted hard drive cage also helps. You could even fit one of the original Delta 120x38mm fans for improved airflow (at the expense of even more noise!)
You could go crazy and fit a Delta or San Ace 120x72mm fan (complicated and difficult to fit), if you can find one and don't mind yet more noise.

Water cooling is always an option — with all the usual proviso's — please, please send me the unwanted copper heat sink.
 

crewkid89

macrumors regular
Original poster
Jun 16, 2011
242
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United States
I would still replace the thermal paste, which is quite easy by the way. Should help lower the temperature further. Here is the service manual, in case you need it: http://tim.id.au/laptops/apple/powermac/pmg4_mir_fw800.pdf
Wow thanks! That's a nice manual. You're right. That looks pretty easy. I don't know why I thought it would be significantly different than doing it on a PC. I think I've got some Arctic Silver around somewhere as well as the cleaner. I'll give that a shot tonight.

I personally would also recommend 2 fans at the back of the case, I have a pair of Fractal Design Silent Series R3's, they bring CPU temps down by around 10°C and fit between the (non-copper) heat sink and the metal inner case mesh very nicely.
Would a PCI fan be a good replacement for that? There are a couple PCI cards in the machine I don't really need. It's got an extra network card (I think it was used as a server) and it's also got a card for extra firewire ports which I don't need. The only thing in a slot that I need is the graphics card and it's AGP.
 

oi!

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Jan 10, 2016
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I'd recommend a PCI fan (or 2) as well rather than instead of the 2 rear mounted fans. They are a bit fiddly, but they're a very worth while mod, IMHO.

A 4 or 5 port USB2 card is always handy to have too.
 

MysticCow

macrumors 6502a
May 27, 2013
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Oh those are quite normal, I MEAN, uh, horribly abnormal temperatures. Your Mac is now running the risk of...uh...sprouting ASSIMILATION TUBULES and assimilating you. Yeah, that's it. It's best to send to me, so that I can work on it and--

*feels tap on shoulder from MacRumors Mod*

NO! YOU WON'T TAKE ME BACK TO THE NAUGHTY STOOL! I WILL NOT GO! I'LL SUE! I'LL--

(fake mod note: We're just not going to let him off the naughty stool this time)
 
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eyoungren

macrumors Core
Aug 31, 2011
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Oh those are quite normal, I MEAN, uh, horribly abnormal temperatures. Your Mac is now running the risk of...uh...sprouting ASSIMILATION TUBULES and assimilating you. Yeah, that's it. It's best to send to me, so that I can work on it and--

*feels tap on shoulder from MacRumors Mod*

NO! YOU WON'T TAKE ME BACK TO THE NAUGHTY STOOL! I WILL NOT GO! I'LL SUE! I'LL--

(fake mod note: We're just not going to let him off the naughty stool this time)
Keep trying. Some day you may get a Mac in the mail that isn't yours and you weren't expecting. :D
 
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MysticCow

macrumors 6502a
May 27, 2013
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Keep trying. Some day you may get a Mac in the mail that isn't yours and you weren't expecting. :D
I'm really hoping for a G4 mini, which can run MorphOS right out of the box. If I ever get some spare money (my dear, sweet, and wonderful prevents this a lot) I will get one.
 
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LightBulbFun

macrumors 68020
Nov 17, 2013
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I'm really hoping for a G4 mini, which can run MorphOS right out of the box. If I ever get some spare money (my dear, sweet, and wonderful prevents this a lot) I will get one.
Looking at your signature I see a couple of Macs that can run Morph OS OOB your 733 DA and your G5 (depending on graphics card) should run Morph OS OOB (I had no issues Running Morph on both my G5s from a USB stick)

also at the OP Damn you got lucky that Radeon 9700 Pro Mac edition Card is VERY Rare and worth more then the entire MDD it self id say...
 

MysticCow

macrumors 6502a
May 27, 2013
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Looking at your signature I see a couple of Macs that can run Morph OS OOB your 733 DA and your G5 (depending on graphics card) should run Morph OS OOB (I had no issues Running Morph on both my G5s from a USB stick)

also at the OP Damn you got lucky that Radeon 9700 Pro Mac edition Card is VERY Rare and worth more then the entire MDD it self id say...
Well, the G5 is acting very weird right now, so it's going to need a good cleaning and redoing of the thermal paste. I might try it after I get it fixed up as a dual Morph/Mac OS machine. Maybe.
 
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MysticCow

macrumors 6502a
May 27, 2013
844
394
The MDD was one of the best power mac's they ever made still have mine its 14 years old and works great still
They're the best OS 9 machines as well. Actually, the single processor one is, as the dual gets wasted unless the app is specifically coded to take advantage of the second processor. That didn't happen very often under OS 9.
 
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