Resolved MAC PRO 4,1 and 5,1 PCIe AUX Power

[JeDiGM]

After reading this thread it became obvious that to be “safe” while using a power hungry GPU like the Radeon VII it was best to go with the pixlas mod. It wasn’t so hard to do and with the cable behind the fan and an EVGA powerlink it looks pretty good too.

F*#k that's clean. Nice job. I'm going to try to get mine that clean LOL.

 

[Itconnects]

It still seems to me, that the safest option (for internally powering a big gpu) is to use a combiner cable to feed 150w from both mini 6 pins into a single 8-pin cable, then use an adapter to send power to the 6-pin port from one of the internal SATA connections (which I was told is capable of supplying up to 54w).

This would give you:
- 75w from PCIe port
- 150w from dual mini 6-pins
- 54w from SATA connection

For a total of 279w, which should cover a Titan X (which is the beefiest thing you can currently put into a cMP).

*Someone please correct me, if I've got those numbers wrong.

For the sata connections, all I see online are 15pins, how does that work? Or must it be 22 pins

 

[mikas]

15 pins.

You would want a 2x SATA power to 6-pin cable though.
One can not know if the GPU will pull more than 54W (1xSATA power max spec) at its 6-pin connector, so you better feed it from 2x SATA power (=108 max spec) just to be at the safer side of not burning anything.

SATA - Wikipedia

en.wikipedia.org

SATA Data = 7 pins
SATA Power (standard connector) = 15 pins (3.3V, 5V, 12V)

 

[theirongiant]

Anecdotal evidence about power consumption:

I have undervolted the MSI Vega 64 and raised the power threshold to +50%. Tests conducted in Furmark for Windows at 4K windowed so I can monitor the GPU stats using the overlay provided by AMD Radeon software. I also have a Cyberpower UPS with digital watt meter and the numbers line up.

Drawing power from the PCIe slot + (2 x mini6-to-8pin) power cables and bridging everything through an EVGA PowerLink, the Vega 64 can pull about 275W sustained for 5-10 seconds before the power supply detects an over-current condition on the AUX lines and shuts down the computer.

If I add a third power source—2xSATA-to-8pin, taken from the backplane SATA plugs—the card may consume around 330W and stay there as long as the fan keeps up. The card's BIOS appears to throttle power output after a certain point to keep the card from melting itself. Maybe the watercooled versions are capable of maintaining full power under maximum load.

 

[shadethegrey]

I don't know why, but I haven't seen anyone ask apple support for the official numbers for the Aux connectors on the cMP. So I called, an extremely helpful gentleman sent a question to the engineers, and 4 days later they responded that it was designed for 75 watts per 6 pin connector plus the 75 watts from the slot. No More. It is built to take some surges, but running it higher than that is at your boards own peril.
I was asking in reference to a Vega 56 and they said if I ran that use an external power supply (or Pixla's mod).

 

[fabj]

Hi!
During the last weeks, I built up my cMP 4,1->5,1 with the help of the great threads here and at Greg Gant's blog.
Now I found myself struggling with the topic of power supply, and I admittedly have difficulties putting all the information in this thread together in a way I feel safe with:

- I got a Red Dragon Vega 56 GPU, supposedly drawing 185/165 Watt, depending on BIOS switch
- I connected it using a dual mini-6-pin to 8-pin cable just like this
- GPU remains idle when I start the machine. (Changing back to GT 120 GPU works fine, though.)

Just above, I read Pixlas mod is recommended for such a setup. So I might consider that. Nevertheless, what I did not get yet:
- even in case of being insufficiently powered, shouldn't the GPU at least turn on when booting? (it's a used one so I might want to return it)
- is it fine to use only the 8-pin connector on the GPU or would anything change if I make use of the 6-pin connector additionally (I understand that an additional SATA wire is not recommended, but what if I use to distinct single mini-6-pin connections?)

Thanks for any hint!

 

[Macschrauber]

if it has 2 power connectors 6+8 you'll need to power both of them.

To test this you can get a 8pin to 2x 6+2 pin cable and plug it in the 2xmini6 to 8pin cable to balance the power of both mini 6 pin on the backplane board.

depends what the card draws from the connectors it is usable. You must not exceed 220 Watt Power of both of those mini 6 pin connectors.

 

[shadethegrey]

Macschrauber is right. You need both of the connections for it to work, it may look like it powers on, but it won't do anything. I've heard some of the 6+8 power arrangements don't load balance very well either, they tend to draw more off of the 8 pin. I don't want to be pessimistic, but that Vega56 will most likely exceed 220 watts at full tilt. The Red Devil version runs past 400 watts on load and my MSI vega 56 air boost ran close to 300. Vega cards are VERY power hungry. I do like how mine runs though, very happy with it. I would HIGHLY recommend doing the pixlas mod on your mac if you run that card. Your mileage may vary, batteries not included, not a flying toy.

 

[fabj]

To test this you can get a 8pin to 2x 6+2 pin cable and plug it in the 2xmini6 to 8pin cable to balance the power of both mini 6 pin on the backplane board.

Thanks! Just put in into the shopping cart.

And I have one more question:
I got two PCIe extension cards:
- USB-C interface: This one‘s got an internal 15 pin SATA power supply connection. Is it intended to be connected to one of the SATA ports on the logic board in case I need additional power for supporting external drives or charging devices connected via USB-C? Or is there any other way to make use of that connection (it wouldn‘t work vice versa, I suppose)?
- Wifi card with Intel AX200 chip: A bluetooth USB cable is included here. Using a cable extension, I guess I can connect it to the socket used for the original bluetooth adapter. Am I right about that?
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Vega cards are VERY power hungry. I do like how mine runs though, very happy with it. I would HIGHLY recommend doing the pixlas mod on your mac if you run that card.

Thanks for sharing experiences! Going through it, I wonder whether
- would I be safe to max out my setup (once working) for test purposes without additional power supply or can I destroy PSU/GPU … doing so?
- would anything change regarding your recommendation given I switch to an RX580? My foremost goal is to get Mojave booting on a reliable yet powerful setup, I‘m not a frame rate junkie (yet).

 

[Macschrauber]

The math is simple:

8 pin 150 Watt max
Plus
6 pin 75 Watt max
-----------------------
225 Watt from the pcie power connectors

If well balanced and if one is not full throttling the card a balanced construction will fit.

Practice shows the max is about 110 Watts per mini 6 until the machine shuts down.

If it is a computing and rendering rig I would take the Pixlas way.

If its a normal rider then balanced power should fit.

 

[shadethegrey]

On the usb card, I have a 2 port USB 3 card that has a power connector that plugs into a sata port for power. It seems to work fine for that for me. I did have to clip one side of the cable plastic so it would plug into the mac pro's sata power.

You can run what you have, and see if it shuts down. If it does, you know you need to mod the power feed or go with a less power hungry card, like the 580 you mentioned, as long as it isn't wildly overclocked from the factory. The Vega will perform better, but at a cost of power. It is amazing to see these old Macs still being able to run some newer stuff with gusto, a testament to their build quality. You can mod these things 9 different ways and they still hold up.

 

[Chips Stephens]

I have glanced over all this fussing with
How much power a person can drag through an old Mac backplane, why?
Why do people insist on trying to drag power across on old backplane, it is just laziness?
the capacitors on that board are how old?
What ever number that 6 pin supported as new, “just to be clear”
Is NOT what it will do today, due to esr, and leakage at rated voltage, the caps are well beyond expected life at this point.
75 watts on every Mac pro is NOT a constant! as many here claim, and exactly why some shut down and others do not.
Pixlas it, it’s easy, it cost less, your backplane will last longer.

the Mac Pro was never designed to run a modern video card across the mini 6 pins at the level people do now adays.

the power supply was very overbuilt.
The mini 6 pin was not.
Get power from the correct place.
Or burn out your backplane.
It’s just a matter of time.

just an engineer.....and his two cents.

 

[Fcis]

Thanks! Just put in into the shopping cart.

And I have one more question:
I got two PCIe extension cards:
- USB-C interface: This one‘s got an internal 15 pin SATA power supply connection. Is it intended to be connected to one of the SATA ports on the logic board in case I need additional power for supporting external drives or charging devices connected via USB-C? Or is there any other way to make use of that connection (it wouldn‘t work vice versa, I suppose)?
- Wifi card with Intel AX200 chip: A bluetooth USB cable is included here. Using a cable extension, I guess I can connect it to the socket used for the original bluetooth adapter. Am I right about that?
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Thanks for sharing experiences! Going through it, I wonder whether
- would I be safe to max out my setup (once working) for test purposes without additional power supply or can I destroy PSU/GPU … doing so?
- would anything change regarding your recommendation given I switch to an RX580? My foremost goal is to get Mojave booting on a reliable yet powerful setup, I‘m not a frame rate junkie (yet).

I wonder what did you end up doing regarding both the USB-C PCIe card and the Bluetooth. Which cable did you use to get power from the sata port to the USB-C card? and did the bluetooth card worked well?

 

[fabj]

I wonder what did you end up doing regarding both the USB-C PCIe card and the Bluetooth. Which cable did you use to get power from the sata port to the USB-C card? and did the bluetooth card worked well?

The USB-C-card has been working well without the additional power connection: Even with a Thunderbolt 3 external SSD it runs at convenient speed. I never tried to attach a 3,5" HDD which might require extra power though.

Regarding Wifi 6 / Bluetooth Chip: That Intel AX200 seems to be incompatible with Mac. I found this, but it seems to be unreliable: https://github.com/OpenIntelWireless/itlwm. Typically, this one is used instead: https://www.ebay.de/itm/392642445568. I have not ordered it yet, since I have been using 1 GBit Ethernet and the old Bluetooth chip is sufficient for Magic Trackpad 2.

 

[farikatik]

mac pro 3.1 - Isn't it easier to power all SATA (8 pcs) from an additional 300-500W power supply plugged into the place for a DVD drive???
to direct the power reserve to power the GPU?

 

[Grindhouse]

You all lost me somewhere in the middle

Is there a simple answer for a noob on this?

I have a EVGA GEFORCE GTX 680 CLASSIFIED and it needs:
- 550 Watt or greater power supply with a minimum of 38 Amp on the +12 volt rail.
- PCI Express, PCI Express 2.0 or PCI Express 3.0 compliant motherboard with one graphics slot.

The card has 2 x 8 pin connector. With the 6 to 6 pin connector I get an error saying that I need to connect the power cable(s). Is it safe to get a 6 to 8 pin cable to make it go? And will it go? Any suggestion on which cable?
Cheers!

Mac Pro 5.1 mid 2010

 

[mikas]

For that kind of a card I think you really would want to perform the Pixlas mod.
EVGA GeForce GTX 680 Classified Review: Pushing GTX 680 To Its Peak
"EVGA’s default power target on the GTX 680 Classified is 250W (330W if using +132% power target), versus 170W(225W w/+132%) on the reference GTX 680"

There is a chance you could get byt with 2x 6-pins + 2x SATA power through an EVGA powerlink. But I would not suggest that because there are risks involved with that approach.

 

[Grindhouse]

For that kind of a card I think you really would want to perform the Pixlas mod.
EVGA GeForce GTX 680 Classified Review: Pushing GTX 680 To Its Peak
"EVGA’s default power target on the GTX 680 Classified is 250W (330W if using +132% power target), versus 170W(225W w/+132%) on the reference GTX 680"

There is a chance you could get byt with 2x 6-pins + 2x SATA power through an EVGA powerlink. But I would not suggest that because there are risks involved with that approach.

Thanks very much for that answer. I don't have the skills to mess around with the Pixlas mod. I was thinking of an aux power, maybe a simple PC power supply just for the card. Set it next to the Mac... But maybe it's better to sell it and find a compatible card. Cheers!

 

[rx78]

Thanks very much for that answer. I don't have the skills to mess around with the Pixlas mod. I was thinking of an aux power, maybe a simple PC power supply just for the card. Set it next to the Mac... But maybe it's better to sell it and find a compatible card. Cheers!

I've gone down the ATX PSU route to power my Vega 56 as I too did not want to Pixlas mod (I don't have confidence in my ability)

You'll need an add2psu board, a SATA to MOLEX cable, an unused SATA port (I used hard drive bay 4) connect them up and then it should be fine but you will need to find some way to manage the cables going in and out of the mac. I used to have them running through an empty PCIE slot but then decided to drill a hole in a spare side panel and have them snake out that way.

Then I decided to go without the side panel.

Works a treat.

 

[Grindhouse]

mightI've gone down the ATX PSU route to power my Vega 56 as I too did not want to Pixlas mod (I don't have confidence in my ability)

You'll need an add2psu board, a SATA to MOLEX cable, an unused SATA port (I used hard drive bay 4) connect them up and then it should be fine but you will need to find some way to manage the cables going in and out of the mac. I used to have them running through an empty PCIE slot but then decided to drill a hole in a spare side panel and have them snake out that way.

Then I decided to go without the side panel.

Works a treat.

Oh, there's more to it than to just plug it in a atx psu?! If I was sure about the ability to flash the 680 Classified I might had give it a go. But I think I'm going to do some more research and make sure to get an out of the box and ready to go GUI. Nothing fancy, just good enough to get Catalina up and running so I can update Logic X. Thanks for the help!

 

[DJP 708]

Yes.

The Mac Pro 4,1 | 5,1 will provide 150 watts for each 6 pin plug. Why? The 8 pin plug has 3 - 12 volt pins and provides 150 watts. The 6 pin plug is specified to only have 2 - 12 volt pins and provides 75 watts. But many manufactures deliver 12 volts on all 3 pins on the 6 pin plug. So why is there an 8 pin plug if 6 pin plugs can give you 150 watts. Because not all 6 pin PCIe AUX plugs have all three power pins connected. But in the case of the MAC PRO 4,1 | 5,1 all 3 pins are connected, the same 3 pins on the 8 plug. 8 pin plugs are only around to ensure pin number 2 is also powered. It is my understanding many manufactures connect pin number 2 in the 6 pin plug, but it is not guaranteed. So thats why we have 8 pin plugs.
[doublepost=1488680084][/doublepost]

Again this is on the MAC PRO 4,1 | 5,1. All three power pins are connected, the same three pin on the 8 pin plug. So yes you will have 150 watts from this motherboard. You just need the correct 6 to 8 pin plug. In the picture you can see the additional pins are just jumpers.
View attachment 690998

Where can I find this ? Or buy one from ? I’m in a stump right now and I’m new to this

 

[MacNB2]

Where can I find this ? Or buy one from ? I’m in a stump right now and I’m new to this

Search for "Dual Mini 6 Pin To 8 Pin Male PCI-E Power Cable For Mac Pro Video Card" like one sold on UK Amazon:

DyNamic Dual Mini 6 Pin To 8 Pin Male PCI-E Power Cable For Mac Pro Video Card 01

DyNamic Dual Mini 6 Pin To 8 Pin Male PCI-E Power Cable For Mac Pro Video Card 01

www.amazon.co.uk

The two mini 6-pin plugs onto the Mac Pro AUX sockets and the 8-Pin end plugs into the GPU.

If your GPU demands 8-Pin AND 6-Pin plugs on the GPU, then you can add a "8-pin to 8+6 Pin adapter" to the above cable. Such as this:

8Pin PCI-E PCI Express Graphics Video Card 8 Pin GPU VGA Female to Dual 8Pin (6+2) Pin PCI-E Male Y Splitter Power Extension Cable 8 Pin GPU molex for Graphics Card BTC Miner 20cm (10 pieces)

GPU PCIE 8-Pin to Dual PCIe 8 Pin (6+2) Converter The GPU PCIE 8-Pin to Dual PCIe 8-pin Adapter Power Cable provides a convenient solution for powering a video graphics card from a PSU with only a GPU PCIE 8-Pin power connection. Standard 18AWG Wire for Better Power Supply Use standard 18AWG UL10...

www.amazon.co.uk

This is all assuming that the GPU you wish to use is within the power level capacity of the 2 mini 6-Pin AUX connectors PLUS the PCIe bus supply (75W).

What GPU are you planning on using ?

 

[farikatik]

View attachment 827268
Съемные вкладки питания от Powerlink.

View attachment 827268
Removable power tabs from a Powerlink.

That is, there is one big plus and one big minus on each connector?
What if you just solder 5 plus wires and three minus wires together on connector 8?
and in exactly the same way on connector 6, solder three plus and three minus wires together in the middle???