Mac Mini G4 heat, noise and power consumption

[Roman78]

Just started playing whit one of my G4 Mini's and i thought about the heat, noise and power consumption.

One thing i noticed about Apple hardware, is that they are always getting to hot. So i always install Mac Fan Control and tune the fans to higher speed. As that is on the new Intel based Apple Computers. On the older once I am not able to read the CPU temperature, nor can i control the fans by software.

Now i have 2 Mini's G4 1.43 overclocked to 1.5 Ghz. No I installed OS 9.2 on one of it to play some games and user older Software. Mostly software that runs perfectly on 333 Mhz or less. So 1.5 Ghz is for the most software a totally overkill. So time to underclock. But what will the difference in heat, noise and Power Consumption be? Did someone made a test of this? And are there more possibilities than 1.25 - 1.58 Ghz?

There a 4 resistors that sets the multiplier. So there are 16 Possibilities, but I only found four settings online. I came up whit the idea to ad 4 switches to the mini to control the MP. So i could change the speed every time i boot the system. When i know more about the 16 Possibilities I could make a Turbo button, just like on the old 80's DOS computers.

(c) Picture from my blog: http://www.die-oswalds.de/blog/2016/04/18/macmini-g4-uebertakten/

[IIO]

biggest part of the power consumption is probably your GPU usage. in other words, "playing games" is mainly responsible for your heat issues.

[Roman78]

hmmm is the Radeon 9200 that power hungry? And it does not even have a cooler, it just has that aluminium plate on the bottom.

Just googled the CPU an according to Wiki is a 7447A in the Mini and that has a TDP of 29 Watt at Max. Pity the didn't used the 7448 in it. Only 10 Watts at 1.5 Ghz.

More important is the head. If it needs 29Watt it has to release the 29Watt of heat somewhere. And the colder a CPU the longer it lives. I think i have to make some test...

[darthnVader]

Just started playing whit one of my G4 Mini's and i thought about the heat, noise and power consumption.

One thing i noticed about Apple hardware, is that they are always getting to hot. So i always install Mac Fan Control and tune the fans to higher speed. As that is on the new Intel based Apple Computers. On the older once I am not able to read the CPU temperature, nor can i control the fans by software.

Now i have 2 Mini's G4 1.43 overclocked to 1.5 Ghz. No I installed OS 9.2 on one of it to play some games and user older Software. Mostly software that runs perfectly on 333 Mhz or less. So 1.5 Ghz is for the most software a totally overkill. So time to underclock. But what will the difference in heat, noise and Power Consumption be? Did someone made a test of this? And are there more possibilities than 1.25 - 1.58 Ghz?

There a 4 resistors that sets the multiplier. So there are 16 Possibilities, but I only found four settings online. I came up whit the idea to ad 4 switches to the mini to control the MP. So i could change the speed every time i boot the system. When i know more about the 16 Possibilities I could make a Turbo button, just like on the old 80's DOS computers.

(c) Picture from my blog: http://www.die-oswalds.de/blog/2016/04/18/macmini-g4-uebertakten/

Apple went cheap on the G4 Mini and didn't use a chip that could report temps, or control the fans the way that the iBook G4's and Powerbook G4's that use the 7447a can. I can't find anywhere in the IOReg that the temps of the G4 Mini are reported to the OS, nor is there any sort of fan control for the OS.

It seems the must be some sort of temp and fan control, but it must be handled by the Boot logic and never exposed to the OS.

The iBook and Powerbook (7447a) use the ADT7467 chip and can be controlled with:

https://github.com/andreafabrizi/G4FanControl

The Mini G4 lacks this, and I assume it has some sort of diode maybe connected to the heat sink, that is wired to some logic for the fan, as the heat raises on the heat sink the resistance of the diode likely changes, and the fan ramps up.

The 7447a can do dramatic frequency scaling, and that maybe be exposed to the OS, someone would have to check the 7447a data sheets to see if there is a way to leverage that.

 

[ELN]

OS X can wang the PMU to adjust fan speeds, but OS 9 cannot. The PMU does fine on its own, perhaps erring slightly on the fast side.

With my fixes to the NanoKernel, the correct power management calls will be made to reduce power consumption while the CPU is idle. Underclocking probably won’t improve things.

[IIO]

i have no ides if the mini GPUs are "normal" 9000/9200 or if they are downscaled "SE" versions. the normal ones would consume up to 17 watts when i remeber right, and that is 50% more than the later integrated intel graphics.

but of course a radeon solution is also the better solution. the core2duo minis dont even give you a proper 1920*1200 image via VGA, i connect mine with DVI... the G4 works perfectly.

[darthnVader]

OS X can wang the PMU to adjust fan speeds, but OS 9 cannot. The PMU does fine on its own, perhaps erring slightly on the fast side.

With my fixes to the NanoKernel, the correct power management calls will be made to reduce power consumption while the CPU is idle. Underclocking probably won’t improve things.

Did you leverage the HID1(DFS2) bit?

Do you know what bit that is, Reggie SE doesn't have any info on that bit.

Better Performance seems to give a value of 0x8000FC80

While Better Battery Life gives a value of 0x8040EC80

So that's a change of bits 9 and 19, but writing that value seems to clause  a hard lockup of the machine, so there must be some additional logic to it.

BTW the 7447a data sheet says it has a thermal diode, ELN, any idea how the Mini may use this to control the fan?

[darthnVader]

OS X can wang the PMU to adjust fan speeds, but OS 9 cannot. The PMU does fine on its own, perhaps erring slightly on the fast side.

With my fixes to the NanoKernel, the correct power management calls will be made to reduce power consumption while the CPU is idle. Underclocking probably won’t improve things.

Did you leverage the HID1(DFS2) bit?

Do you know what bit that is, Reggie SE doesn't have any info on that bit.

Better Performance seems to give a value of 0x8000FC80

While Better Battery Life gives a value of 0x8040EC80

So that's a change of bits 9 and 19, but writing that value seems to clause  a hard lockup of the machine, so there must be some additional logic to it.

BTW the 7447a data sheet says it has a thermal diode, ELN, any idea how the Mini may use this to control the fan?

Bit 9 is the DFS2 bit, and bit 19 seems to be the PLL configuration mode, bit 4.

I'd like to be able to know how to manually set Bit 9 on/off without locking up the system?

 

[darthnVader]

According to PowerLogix:

PowerPC 7447A upgrades support a new feature called "dynamic frequency switching" (DFS).  DFS allows the processor to be slowed to half its regular speed to conserve power while the processor is idle.  DFS is enabled by selecting the desired processor speed in the Energy Saver preference panel.  By selecting "Reduced", the processor will always run at half its regular speed.  Conversely, by selecting "Highest" the processor will run at maximum speed.  By selecting "Automatic", the processor will switch between reduced and highest performance based on CPU demand.  "Automatic" is the recommended setting.  DFS is only available on Mac OS X 10.3.9 and later, and it only works on CPU cards configured with integer bus ratios. (DFS works by cutting the PLL ratio in half. For example, a 1500 MHz CPU with 100 MHz bus is a 15:1 ratio. Half of 15 is 7.5, so when DFS is active, the clock speed with be 750 MHz. However, if the machine is set to 1800 MHz with 133 MHz bus, for example, this is a 13.5:1 ratio, which is not an integer. A bus ratio of 6.75:1, is not possible, so DFS will not work in that case.)

This means the 1.25 Ghz and 1.42 Ghz Mini will not support DFS, as they have 7.5/8.5 bus multipliers.

Time to overclock my 1.42 Ghz Mini to 1.5 Ghz, so I can use DFS?

The required software sequence for setting or clearing the HID1[DFS2] bit
is as follows:
sync
mtspr HID1
sync
isync

Dynamic frequency switching (DFS) divide-by-two mode.
0 DFS divide-by-two mode is disabled.
1 DFS divide-by-two mode is enabled.
Note that the divisors are only applicable to the processor-to-system ratio chosen at
reset by the external PLL_CFG pins. If the HID1 settings select a ratio that is not
supported (see the MPC7447A RISC Microprocessor Hardware Specifications or
MPC7448 RISC Microprocessor Hardware Specifications for supported ratios), the
setting of the HID1[DFS2] bit is ignored.

[Roman78]

What is DFS.. Directory File System??

Hmmm So i made some test. I soldered 5 wires to the Mini's Logicboard and connected 4 switches to test the Multipliers. The lowest i got was 1080 and the highest 1920, but that hang. See pictures below (how can i place those in here?). At 1080 the mini consumes 6 watt less. So if it is only CPU that the MP has effect of it has 6 watt less heat. Maybe we could make it a passive cooled computer Hmmm need bigger cool block for that.

[MacTron]

What is DFS.. Directory File System??

Hmmm So i made some test. I soldered 5 wires to the Mini's Logicboard and connected 4 switches to test the Multipliers. The lowest i got was 1080 and the highest 1920, but that hang. See pictures below (how can i place those in here?). At 1080 the mini consumes 6 watt less. So if it is only CPU that the MP has effect of it has 6 watt less heat. Maybe we could make it a passive cooled computer Hmmm need bigger cool block for that.

Over 1.5 Ghz you'll probably should increase the CPU voltage ...

[darthnVader]

What is DFS.. Directory File System??

Dynamic frequency switching (DFS) divide-by-two mode.

So if you have it set to an integer multiplier, then it would scale the CPU 1/2.

BTW there are 5 PLL's, you missed one, likely PPL_CFG0.

[ELN]

Did you leverage the HID1(DFS2) bit?

Do you know what bit that is, Reggie SE doesn't have any info on that bit.

Better Performance seems to give a value of 0x8000FC80

While Better Battery Life gives a value of 0x8040EC80

So that's a change of bits 9 and 19, but writing that value seems to clause  a hard lockup of the machine, so there must be some additional logic to it.

BTW the 7447a data sheet says it has a thermal diode, ELN, any idea how the Mini may use this to control the fan?

Easy answer: the NanoKernel never touches HID1. I couldn't say for sure about the CPU Plugin, so check that separately.

The NK's internal idle task sets HID0[DOZE/NAP/SLEEP] according to an internal table looked up by PVR. It then sets MSR[POW] to enter the selected state. The PowerPC exits the state when an interrupt occurs (most likely external or decrementer).

Some members of the 7450 series ("G4e") have a thermal diode on-die, exposed directly through the socket. This includes the 7447a but I think not the plain 7447. None have the THRM* registers required to read its state from PowerPC code. So I'd guess that any software diode goes through the PMU. I think the OF device tree reflects this.

[Roman78]

What is DFS.. Directory File System??

Dynamic frequency switching (DFS) divide-by-two mode.

So if you have it set to an integer multiplier, then it would scale the CPU 1/2.

BTW there are 5 PLL's, you missed one, likely PPL_CFG0.

I missed one? Where is the fifth than. I only found information about this 4. Have you some more information?

/edit: i think i found it. Almost every side is only talking about those for except this http://www.overclock.net/forum/251-mac/1445164-ultimate-mac-overclocking.html they also talking about 5, the R52 it is. So back to the hobby room. Unfortunately they are linking to a dead site. What does the R52 do.

Is there a way to change the FSB also? Whit a lower FSB the whole Logicboard will run lower, also the GPU.

So now i know it is the R52 i did an explicit search on it. Another site tells me, that it is under the cooler and i only have to change it, when i want to go above the 1.58 Ghz. Hmmmm is it worth a try?

[IIO]

that it is under the cooler and i only have to change it, when i want to go above the 1.58 Ghz. Hmmmm is it worth a try?

thats why most people do 1.5 GHz, they just remove these 4 and then cant go back to anything else.

[darthnVader]

The Mini uses the MAX662 I2c controller for temperature control logic, however it doesn't report it's values via the IOReg, that I can find.

https://datasheets.maximintegrated.com/en/ds/MAX6625-MAX6626.pdf

Tho we maybe able to take the source for G4FanControl and get something working for OS X.

I'm unsure if it's a 6625 or 6626.

[darthnVader]

What is DFS.. Directory File System??

Dynamic frequency switching (DFS) divide-by-two mode.

So if you have it set to an integer multiplier, then it would scale the CPU 1/2.

BTW there are 5 PLL's, you missed one, likely PPL_CFG0.

I missed one? Where is the fifth than. I only found information about this 4. Have you some more information?

/edit: i think i found it. Almost every side is only talking about those for except this http://www.overclock.net/forum/251-mac/1445164-ultimate-mac-overclocking.html they also talking about 5, the R52 it is. So back to the hobby room. Unfortunately they are linking to a dead site. What does the R52 do.

Is there a way to change the FSB also? Whit a lower FSB the whole Logicboard will run lower, also the GPU.

So now i know it is the R52 i did an explicit search on it. Another site tells me, that it is under the cooler and i only have to change it, when i want to go above the 1.58 Ghz. Hmmmm is it worth a try?

Checkout section 9.1.1 on page 34-35 Table 13.

https://www.nxp.com/docs/en/data-sheet/MPC7447AEC.pdf

[Roman78]

Thanks for the PDF. According to table 13 it is worth trying.

There it says that 01111 = 1.5 Ghz. Now i have to figure out which is which. First of all its kind of inverted (like 1 is off) because the 1.5 Ghz is made by all resistors removed.

When i compare table 13 to my table i got the following:

the 1st is R52
the 2nd is R351
the 3rd is R358
the 4th is R362
and the 5th must be R355

Am i right?

And according to Table 7 the power consumption of a 1.42 is 30 watt max and the 1.0 does 23 watt.

My idea is, that when you lower the clock it will have a positive effect of the life length of a CPU. Overclocking is soooo nineties.

Does someone know about a possibility to lower the FSB? According to table 13 when running at 1.5@167FSB and changing to 100FSB it will do 900Mhz. Or maybe on 67Mhz will do 600Mhz CPU.

[Roman78]

I removed the cooler and found the R52. Next to a lot other resistors. Damn they are small.

So i thought to let it go.

But than i noticed the CPU is a MC7447B and than HX1500QF. Does this means it is a 1.5 Ghz CPU? Could not find anything about this cpu.

[ELN]

You might be on to something. Very cool!