ATX PSU conversion Powermac G3

[Laterne]

Finally my original G3 beige's PSU died. So I took the opportunity to convert to an 80 Plus Gold certified one.

There were three reasons for upgrading:

1. active PFC => high efficiency ; low consumption
2. ultra silent operation of the 120 mm PSU fan being temperature-controlled
3. almost doubled nominal power output


To fit the G3 Mini-Tower case without modifications the PSU has to be ATX form factor. The correct location of the power unit's On/Off switch is another aspect to be considered.

Some general info:
Both beige G3 cases - the Desktop and the Mini-Tower - feature the Gossamer mainboard, but only the latter was shipped with an ATX-based power supply. Before converting to an actual ATX PSU make sure the small PSU-specific jumper (found on the mainboard in the vicinity of the PCI expansion slots) is set to PS/2 position.

In addition, two modifications must be carried out in order to make a 24-pin PSU connector work with these old-world Powermacs:

1) pin 18
Since year 2005 most 24pin ATX power units don't carry pin 20 (-5V) any more. So we can take the (useless white) wire of pin 20 to obtain "ground" for G3 pin #18 e.g. by connecting it to black wire of pin24.

2) pin 8
The standard ATX pin #8 called "Power Good" (often grey-colored) is not required because the Powermac's mainboard provides a built-in boot delay. Instead the beige G3 asks for +3.3V ("orange") at pin #8.

I purchased a short ATX wire adapter (24-pin female to 20-pin male) that is well suited for these two mods. You don't have to alter anything at the PSU wiring loom itself!

This modified 24-to-20-pin adapter will allow the following Power Macs to be upgraded with a state-of-the-art ATX PSU:

G3 Desktop
G3 Minitower
G3 All-in-one
G3 Blue & White
G4 PCI Graphics

 

[harrymatic]

Great post, using a modern power supply sure beats hunting down a used or new-old stock one on eBay! I've been considering shoehorning a new PSU into my G4 - I'm just waiting patiently for the original one to die!

 

[Laterne]

Well, for G4 towers such a PSU upgrade will be even more beneficial


Owners of the low height beige G3 Desktop Power Mac also will be able to upgrade to a modern silent and low power consumption ATX PSU.

There are differences though:

The G3 Minitower, G3 B&W and G4 PCI Graphics will accept a standard ATX PSU featuring physical dimensions of 150 x 86 x ... mm using the already present back-plate screw mounting (3 or 4-point).

In contrast to that the stock G3 Desktop PSU (non-ATX jumpered on the mainboard) comes with a custom design of 210 x 86 x 120 mm. And its fan is located at the bottom side.

Such form factor is not available within the actual ATX ranges. Fortunately there's still the regular 30 mm distance between the PSU side panel and the center axis of the AC power connector.

So we can mount most 150 x 86 x ... mm ATX PSUs horizontally in the G3 Desktop (max PSU case depth should not exceed 150 mm).

But, for free access to the AC power connector and to the PSU On/Off switch four short cuts have to be milled into the Desktop's ABS plastic applying a Dremel preferably (see red dashed lines in below picture). This case mod isn't required for the G3 Minitower beige.

Mounting a 150 x 86 x 140 to 150 mm ATX PSU using the regular backplate screws is not realizable in the G3 Desktop sadly. So we should apply strong self-adhesive Velcro strips at the PSU bottom side.

Due to positive long-term experience with these PSU makers and because of the correct position of the ON/Off switch I'd like to recommend the following reasonably priced modern power supply units featuring a temperature-controlled variable speed fan:

• Super Flower Amazon 300 Watt Non-Modular 80Plus Bronze
• FSP Fortron FSP350-60APN(85) 350 Watt Non-Modular 80+ Bronze http://www.fsp-europe.com/professional/pdf/datasheets_psu/fsp350-60apn_85.pdf

They will fit the beige G3 Minitower and G3 Desktop.

In the context of upgrading to an ATX PSU in the Desktop please don't forget to set the jumper to PS/2. Cooling within the G3 Desktop case will change because the internal quiet 120 mm fan of the new PSU now sucks in the air from the top side.

 

[ACD30"]

I'd be interested in trying this on my beige G3 Minitower. To clarify, is the white wire the only wire I need to cut and re-route — does the adapter handle everything else? (I realize this is an old thread, but I am replying because the information is still relevant.)

 

[reddrag0n]

from what i read way back on xlr8yourmac, no mod to any of the wires was nessesary for adding a pc atx psu to a beige G3 after swapping the jumper to PS/2. it handled everything as is.

i can see if i can find the original post on their archives

 

[ACD30"]

from what i read way back on xlr8yourmac, no mod to any of the wires was nessesary for adding a pc atx psu to a beige G3 after swapping the jumper to PS/2. it handled everything as is.

i can see if i can find the original post on their archives

Interesting... I'll look into that.

 

[ACD30"]

from what i read way back on xlr8yourmac, no mod to any of the wires was nessesary for adding a pc atx psu to a beige G3 after swapping the jumper to PS/2. it handled everything as is.

i can see if i can find the original post on their archives

I found this. Someone here claims the same thing you mentioned.

Beige G3 MT Power Supply

My power supply is making a lot of noise.It probably is the fan - but every drive bay is full, this machine has been on 24/7 it's entire life, and I'm wondering if the fan is a sign that it's had its share of wear.http://www.smalldog.com/product/42485$99.00 for a power supply from smalldog.Good...

arstechnica.com

 

[reddrag0n]

on that link that you posted, i found the archived pages they went to.
and yes, there is nothing saying that you have to mod wires to make an atx psu work in a G3 tower.

Converting a Beige G3 Desktop to an ATX Tower

How I Built an ATX Case Beige G3

 

[ACD30"]

on that link that you posted, i found the archived pages they went to.
and yes, there is nothing saying that you have to mod wires to make an atx psu work in a G3 tower.

Converting a Beige G3 Desktop to an ATX Tower

How I Built an ATX Case Beige G3

Thanks for finding those!

I would certainly need to source a power supply from around the early 2000s, though. Modern ATX power supplies are apparently slightly different in how they deliver wattage. They also tend to have an auto start-stop feature for the active cooling, which may not be optimal for a case like this.

 

[reddrag0n]

hmm, i didn't take that into account. i'm just wondering if maybe a modern 500w psu would work instead of putting in a beast like a 700w+ psu

 

[TzunamiOSX]

I see a bigger problem, because the fan is on the wrong side of ATX PSUs. With a ATX PSU the case door is direct to the fan. Normally the fan pulls air over the CPU out of the case.

 

[ACD30"]

I see a bigger problem, because the fan is on the wrong side of ATX PSUs. With a ATX PSU the case door is direct to the fan. Normally the fan pulls air over the CPU out of the case.

Oh, I hadn't realized that. I wonder, then, if I'd be better off retrofitting the stock PSU with a quiet fan (if possible).

 

[TzunamiOSX]

Oh, I hadn't realized that. I wonder, then, if I'd be better off retrofitting the stock PSU with a quiet fan (if possible).

I'm really sure you can replace it. I have replaced the Fan in my G3 Tower with an Enermax fan with termal sensor.

°Here are more informations #15

The grid is not optimal for the rupper pins (look at left and right upper hole) but this is only an optical problem.

 

[ACD30"]

I'm really sure you can replace it. I have replaced the Fan in my G3 Tower with an Enermax fan with termal sensor.

°Here are more informations #15

The grid is not optimal for the rupper pins (look at left and right upper hole) but this is only an optical problem.
View attachment 1948622

Thanks for that! Have you also changed out the case fan?

 

[TzunamiOSX]

Thanks for that! Have you also changed out the case fan?

This is the bigger fan on the PSU who pulls the air out of the case. I’m not sure that I have repaced the small fan inside the PSU of the G3. Berhaps it was the fan inside the PSU of my 9600.

The big was the the noisy.

It is not a problem to replace fans of an old PPC G3 or G4 Mac.

 

[ACD30"]

This is the bigger fan on the PSU who pulls the air out of the case. I’m not sure that I have repaced the small fan inside the PSU of the G3. Berhaps it was the fan inside the PSU of my 9600.

The big was the the noisy.

It is not a problem to replace fans of an old PPC G3 or G4 Mac.

Well, I'll make an attempt at replacing the case fan. I briefly tried finding the model you used, but none of the results are matching; if further searches are similarly unsuccessful in turning something up, I am considering the ARCTIC F12 TC: it has a temperature diode and it's supposedly a quiet fan. Separately, I'm also wondering if a fan w/o PWM (or, 2-pin) would be acceptable.

By the way, how did you wire it? Did you modify it to plug into a fan header, or did you use an adapter to allow it to plug into one of the molex cables?

 

[TzunamiOSX]

Well, I'll make an attempt at replacing the case fan. I briefly tried finding the model you used, but none of the results are matching; if further searches are similarly unsuccessful in turning something up, I am considering the ARCTIC F12 TC: it has a temperature diode and it's supposedly a quiet fan. Separately, I'm also wondering if a fan w/o PWM (or, 2-pin) would be acceptable.

By the way, how did you wire it? Did you modify it to plug into a fan header, or did you use an adapter to allow it to plug into one of the molex cables?

The Enermax was already a discontinued model when i bought him. The ARCTIC F12 TC was my second choice.

Here can you see, why the Everest was my first choice. The Everest has 3 speed modes:

https://www.enermaxeu.com/wp-content/uploads/Support/Discontinued-Products/Fans/Dowloads/everest-adv_datasheet_en.pdf

You can use every standard 3- and 4-Pin fan as a 2-Pin fan. Then the fan is runnig at max. speed because RPM and/or PWM signals are missing. I have used a simple molex to fan adapter to connect the fan.

When the fan ist to loud, you can use a 7V fan adapter (fan + to yellow 12V, fan - to red 5V) to reduce the speed.

7V adapter

My connection

 

[ACD30"]

The Enermax was already a discontinued model when i bought him. The ARCTIC F12 TC was my second choice.

Here can you see, why the Everest was my first choice. The Everest has 3 speed modes:

https://www.enermaxeu.com/wp-content/uploads/Support/Discontinued-Products/Fans/Dowloads/everest-adv_datasheet_en.pdf

You can use every standard 3- and 4-Pin fan as a 2-Pin fan. Then the fan is runnig at max. speed because RPM and/or PWM signals are missing. I have used a simple molex to fan adapter to connect the fan.

When the fan ist to loud, you can use a 7V fan adapter (fan + to yellow 12V, fan - to red 5V) to reduce the speed.

7V adapter

I can see why you chose the Everest; on-the-fly fan control does sound like a nice feature. I'm curious which of the three speeds is optimal for cooling the Mac when it's at load. Would be helpful to find out how much air the default fan moves at full RPM and compare that to the new fan's effectiveness at moving air.

 

[TzunamiOSX]

I can see why you chose the Everest; on-the-fly fan control does sound like a nice feature. I'm curious which of the three speeds is optimal for cooling the Mac when it's at load. Would be helpful to find out how much air the default fan moves at full RPM and compare that to the new fan's effectiveness at moving air.

• Model: Delta Sensflow WFC1212B
• Appearance: 12cm x 12cm x 2.5cm 7 leaves
• Power supply: DC12V 0.44A
• Bearing: Double ball
• Speed: 1245rpm ---- 2447 revolutions (short circuit thermistor)
• Air volume: 44.62 CFM (room temperature)
• Noise: 18 dBA (minimum) ---38DBA
• Wiring: 2 wires
• Line length: 20cm
• Interface: 2pin

I think i have set to Silent Mode with up to 60.11 CFM. The F12 has 53 CFM so run it on 12V. Temp sensor do the rest. In reality the G3 is so cool, im sure you don't need so much fan power.

All PCI slots filled, all drive slots filled, G4 500 inside and nearly no heat in the case. I will check the temp after a heat up test.

EDIT: Temperature inside the case is 27°C with CPU and GPU (Radeon 9200) at 100%
Ifrared thermometer on fan tunnel exit and also SDD sensor.

 

[ACD30"]

• Model: Delta Sensflow WFC1212B ...

Thank you for this information; it has helped me considerably! Either fan looks to be a great choice, so I'll pick whichever is readily available and attempt to install it.

I have noticed that the stock fan pushes what seems to feel like perfectly cool air, which suggests that the G3 barely requires active cooling. If yours is running that cool, I am confident my bone-stock minitower will run exceptionally cool. Anyway, I'll update the thread with my experiences retrofitting the system. Thank you, again!

 

[ACD30"]

Update...

I received the Arctic fan & the 2-pin/3-pin-to-molex adapter. The process of installing the fan looks straightforward, though I do hope that either the included mounting screws fit through the holes on the G3's plastic fan shroud (or, alternatively, that the existing screws fit through the new fan's mounting holes). In any case, I will have to put it on hold until another day: the G3 is full of dust and needs a thorough cleaning before the new fan goes in.

Side note: I noticed that the design entails the fan pulling air up and through an air dam. What's odd is that the air dam is quite shallow and also forms a right angle; this results in the fan having to work against this weird geometry, which I'm guessing causes the fan to sound louder than usual. My hope is that the Arctic is inherently quiet enough to compensate for this.

 

[TzunamiOSX]

Update...

I received the Arctic fan & the 2-pin/3-pin-to-molex adapter. The process of installing the fan looks straightforward, though I do hope that either the included mounting screws fit through the holes on the G3's plastic fan shroud (or, alternatively, that the existing screws fit through the new fan's mounting holes). In any case, I will have to put it on hold until another day: the G3 is full of dust and needs a thorough cleaning before the new fan goes in.

Side note: I noticed that the design entails the fan pulling air up and through an air dam. What's odd is that the air dam is quite shallow and also forms a right angle; this results in the fan having to work against this weird geometry, which I'm guessing causes the fan to sound louder than usual. My hope is that the Arctic is inherently quiet enough to compensate for this.

i have used rubber pins to install the fan

 

[ACD30"]

Another update...

Installation went smoothly (more so than the cleaning process, which has left me coughing)! I didn't use rubber standoffs, but the screws that were included with the fan; everything fit together neatly, and I was able to cleanly route the temperature sensor to the fan grille.

Power up:
Immediately, upon turning the system on, I noticed a significant difference in the acoustics. The new fan is virtually silent, and the noise from the existing PSU fan & the mechanical HDD are now much more pronounced. This is a double-edged sword, really: on one hand, there's far less noise produced... but, on the other, the irritating frequency produced by the PSU fan is much more prominent. Overall, however, I am very pleased with the results! If it's possible, I would very much like to try retrofitting the PSU itself with a quieter fan. I think it's 80mm and has a 2-pin header.

Side note:
I assume that, in spite of the absence of PWM, the fan is being controlled by its built-in temp sensor. That's all fine, but I regret that I have no way of knowing at which RPM it's running. For all I know, it could even be running at too low of an RPM. At least perhaps I could just monitor the temperature (if there's an existing OS9 program for that).

 

[TzunamiOSX]

Another update...

Installation went smoothly (more so than the cleaning process, which has left me coughing)! I didn't use rubber standoffs, but the screws that were included with the fan; everything fit together neatly, and I was able to cleanly route the temperature sensor to the fan grille.

Power up:
Immediately, upon turning the system on, I noticed a significant difference in the acoustics. The new fan is virtually silent, and the noise from the existing PSU fan & the mechanical HDD are now much more pronounced. This is a double-edged sword, really: on one hand, there's far less noise produced... but, on the other, the irritating frequency produced by the PSU fan is much more prominent. Overall, however, I am very pleased with the results! If it's possible, I would very much like to try retrofitting the PSU itself with a quieter fan. I think it's 80mm and has a 2-pin header.

Side note:
I assume that, in spite of the absence of PWM, the fan is being controlled by its built-in temp sensor. That's all fine, but I regret that I have no way of knowing at which RPM it's running. For all I know, it could even be running at too low of an RPM. At least perhaps I could just monitor the temperature (if there's an existing OS9 program for that).

Perhaps this "irritating frequency" is the problem of screws on the new fan. Maybe the vibrations interact.

I cant hear any irritating frequency on my G3 with rubber pins.

Cant find any informations about the internal PSU Fan. The only way to get infos is to open the PSU.
I would say 80mm and delta electronics^^

2 Pin and thermal sensor for sure.

There ist no Program for reading fan informations, because the fans doesn't send any informations. This was the "pre fan information reading time". ?

 

[ACD30"]

Perhaps this "irritating frequency" is the problem of screws on the new fan. Maybe the vibrations interact.

I cant hear any irritating frequency on my G3 with rubber pins.

Cant find any informations about the internal PSU Fan. The only way to get infos is to open the PSU.
I would say 80mm and delta electronics^^

2 Pin and thermal sensor for sure.

There ist no Program for reading fan informations, because the fans doesn't send any informations. This was the "pre fan information reading time". ?

It likely has to do with the fact that the sound of the PSU fan is no longer drowned out, hence why I would like to change said fan as well.

I believe it is indeed an 80mm fan; I opened up a similar PSU (from a graphite G4 tower) and had a look at the internals. It uses a 2-in header, and I believe that the red and black wires on its integrated cable are opposite when compared to those on a typical fan. I may splice into the existing cable, to add whatever new fan I choose to purchase.

Yes, I'm aware that fan stats cannot be monitored — which, if the fan's integrated temperature sensor is in fact doing its job, I'm not too concerned about.