Cube Owners: Artmix VRM II available, slightly updated

[François]

Do we know the power requirements of the CPU upgrades? I’ve noticed the CPU modules (even the stock ones) seems to have a voltage regulator on the board, next to the CPU. So, does the CPU modules really tax the VRM, or are they powered directly from the PSU? (That would explain why they include their own voltage regulator)

 

[Daniël]

Do we know the power requirements of the CPU upgrades? I’ve noticed the CPU modules (even the stock ones) seems to have a voltage regulator on the board, next to the CPU. So, does the CPU modules really tax the VRM, or are they powered directly from the PSU? (That would explain why they include their own voltage regulator)

The Cube's power supply outputs 28VDC. That voltage is then converted by the VRM module to the appropriate voltages such as 12V, 5V, and 3.3V. No accelerator that I am aware of taps the "raw" 28V from the PSU, so it always goes past the Cube's VRM module.

 

[herd]

Was always asking myself… is there a way to do that in OS9 as well?

I don't know anything about OS9, but I saw this posted somewhere: CPU Nap mode defaults to Off after booting OS 9.2.1 and the CPU driver extension for OS 9.2.2 '03 must be copied over to OS 9.2.1 in order to get CPU Nap mode on. The filename is "System Folder/Extensions/Multiprocessing/Apple CPU Plugins" v4.0.1 gives CPU Nap Mode On.

 

[Mikeyy00]

Just to necropost a bit here.

My VRM from Artmix is still busted. He's had it since September "waiting for parts". No updates unless I pester him on ebay messaging.

More of a warning to those who are thinking of buying from him. If repairs are ever needed, ymmv.

 

[Cktwo]

My Artmix VRM still works in my G4 Cube with 1.8 GHz Sonnet Encore. I replaced the stock fan with one I bought since the stock fan only made strange clicking noises but didn't really spin up. The new fan does briefly spin up when the cube is turned on but then stops again. It only starts very reluctantly but at least no clicking noises. I have the impression that the fan is supposed to be temperature controlled. But since documentation on the Artmix VRM is very limited, I don't know if that's true...

 

[Daniël]

My Artmix VRM still works in my G4 Cube with 1.8 GHz Sonnet Encore. I replaced the stock fan with one I bought since the stock fan only made strange clicking noises but didn't really spin up. The new fan does briefly spin up when the cube is turned on but then stops again. It only starts very reluctantly but at least no clicking noises. I have the impression that the fan is supposed to be temperature controlled. But since documentation on the Artmix VRM is very limited, I don't know if that's true...

Looking at the board, it does appear to be temperature controlled. The TC648 IC, located under the 3 pin fan header, is a fan controller, capable of temperature based PWM control, based on temperature readings from a thermistor. Which is precisely what component RT1 is, located right above TC648.

 

[herd]

Do we know the power requirements of the CPU upgrades?

I've been building some CPU upgrades intended for the Cube, so I got out the Cube that I use for testing. To more precisely measure power used by the CPU, I added a shunt to the 5v wire to the CPU. Here is some *peak* power data for a few CPUs I had out:

     650MHz 7410 15.0w
     1.4GHz 7447 17.1w
     1.8GHz 7448 22.8w
dual   1GHz 7447 27.1w
dual 1.5GHz 7448 43.1w

I don't know if there are any specs published for the different VRM upgrades, but this info is relevant. Even assuming an upgraded VRM can handle high power, the PCB traces and CPU connector are showing significant voltage drop at high current levels. Additional wires between the CPU and VRM would help with this.

 

[indibil]

Maybe I'm going to say something outrageous, but I have this question. Just as an ATX power supply can be adapted to the G4 towers, couldn't one of these Pico ATX PSUs be modified to fit in a Cube? With a "big" +12V power supply.

PICO PSU 1

PICO PSU 2

Without the +28V for the ADC, of course.

 

[herd]

That web site tried to do unspeakable things to my computer. I could not easily get much info from it and lost interest quickly. Also, URLs like that will probably be meaningless a few days from now, let alone a few years from now. I would suggest some cut-and-paste type work to put relevant information here.

But I'm guessing the widget you're talking about has a similar function to the VRM in the Cube. So I would say 'yes' it can probably be adapted to serve as a VRM.

 

[indibil]

Sorry, I included a couple of Aliexpress links as examples, but they're sold everywhere. I've attached some photos. They're typical PICO PSUs, and they come in different power ratings. I'd just need to know where to buy the CUBE VRM connector to adapt them to the motherboard. And with a sufficiently sized 12V power supply, maybe can used in a CUBE without the ADC.

 

[herd]

It looks like there are multiple versions. If they're cheap you could test one to see what it can do, and importantly whether it dies in a nice way if it's overloaded or overheated. Do you want more power or just a replacement for a missing VRM in a stock Cube? This is from the artmix web site and might be more believable than lie-express:

 

[indibil]

I don't want to take any credit away from Artmix; on the contrary, I know it won't be comparable to their work. And I'm not suggesting buying it on Aliexpress either; those links were just examples. I usually buy PSUs and similar items from local computer stores; I wouldn't power a Cube with a €12-€15 PSU. I was trying to suggest whether it would be possible to use a PICO PSU in a Cube; there are good-quality PICO PSUs. I don't have a Cube, but a friend has one that wouldn't turn on; it started smoking once and never worked again. The price of Artmix plus customs taxes here in my country is quite high, and we were considering an alternative.

I didn't want to interrupt the post, just suggest alternatives. I've had to revive several QSs with ATX PC power supplies.

 

[herd]

I think some variety of PC hardware could be adapted. Just for testing you could even hook up a regular ATX desktop power supply. But if you have a dead VRM instead of no VRM, it would probably be easier to repair it than to rig up some other new source of power.

To effect a repair, my approach would be to first diagnose the failure. It sounds like some component(s) got very hot and might be easily identified. I would guess the VRM died in some way. In any case, you can try replacing burnt/bad components and see if it comes back to life. Another easy thing to try: use a multimeter to check for shorted FETs. If a high side FET shorted, then the Cube is probably dead.

 

[indibil]

Okay, I'll try that first. When he brings me the CUBE and checks it out, I'll let you know what I find.

Thanks.

 

[herd]

To more precisely measure power used by the CPU, I added a shunt to the 5v wire to the CPU.

Measuring the total power used by a graphics card is more complicated, but I saw a nice project where someone is gathering actual data:

tehsiggi.github.io/agp-power-monitor/

Some of the cards tested are suitable for the Cube.

 

[indibil]

Measuring the total power used by a graphics card is more complicated, but I saw a nice project where someone is gathering actual data:

tehsiggi.github.io/agp-power-monitor/

Some of the cards tested are suitable for the Cube.

This leaves me a bit puzzled, because a few replies ago someone mentioned that maybe the Radeon 9000 was too much for ARTMIX, but according to your graph the Radeon 9000s consume around 15-16W, and as far as I understand the most common replacement for a Cube is a Radeon 7500, which according to this link, has a consumption of 23W.

https://www.techpowerup.com/gpu-specs/radeon-7500.c645

So wouldn't the Radeon 9000 be better than a Radeon 7500 in terms of consumption? just as a 9200 would be better than a 9000.

 

[herd]

As an experiment, I attached a thermocouple to a resistor rated for 1/4w and wrapped it in foam. At 0.1w the resistor was over 100º and it quickly self-destructed at 0.2w. I took another similar resistor, rated for 1/4w, and dipped it in water. How much power do you think it could handle before failing?

 

[indibil]

So, those consumption graphs are of no use to us if the Cube's problem is excessive temperature in that area.

 

[ObeyDaleks]

So, those consumption graphs are of no use to us if the Cube's problem is excessive temperature in that area.

Excessive heat is a failure point for all electronics. But you can definitely reach current limits of the Cube's built-in VRM before heat becomes an issue, especially if you use cooler-running hardware or have a good cooling solution.