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

[h9826790]

In my experience, the readings were quite accurate. It ramped up and down with GPU load.

In my tests, up to 7.99A only, can you get the reading above that?

The top right graph is the power draw. As you can see, during the Furmark test, the power draw will fluctuate, and strangely sharply stay at 96W when the reading is going up. In fact, by comparing to the PSU output and other components power darw. There was about another 50W missing during that test. Which I suspect the cMP has a limitation on that reading. In fact, I can keep increasing the load on the mini 6pins until it shut down, but the reading still 7.99A in iStat (96W in Hardware monitoring).

 

[pastrychef]

I never owned a video card that exceeded 200W and all the video cards I've used with the Mac Pro only used 6 pin power connectors. So, I never came close to 7.99A.

If you're telling me that 7.99A is as high as it goes, it may not be accounting for how much power is being pulled from pin 2...

 

[syops]

Alright another video. This one shows the system consuming 672 watts. The system at idle is 195 watts. That is an additional 477 watts system load to run the 3DMARK Benchmark.

System Idle


GPU Load


GPU Stats



VIDEO

And here is a Liquid cooled Titian X installed in a MAC PRO with the 6 + 8 Pin configuration plugged into the mini PCIe AUX headers. This model has almost the same clocks speeds as the superclock Titian X.

Close up of 6 and 8 pin plugs.



Installed in Mac Pro using mini PCIe AUX 6 pin headers



VIDEO

 

[pierrox]

Running straight of the motherboard??? Wow, this guy has no fear! I would freak out about blowing it up! Or having the MacPro shut down on me every other minute!

 

[pastrychef]

What happens when you run FurMark for a while? Do you have any apps that give amperage readings on the PCI-e auxillary power connectors?

GpuTest - Cross-Platform GPU Stress Test and OpenGL Benchmark for Windows, Linux and OS X | Geeks3D.com

 

[syops]

Ok this does work but research the topic. Make an intelligent choice. If you use something more, it should wear out sooner. Some of these machines are 7 years old and taxing a 7 year old power supply can cause it to reset or become inoperative.

For me these machine are used in a production environment. If they break, I will put new parts in. I have built up two of these Mac Pro 2009s. I de-lidded x5690s, installed faster I/O, and run ASUS STRIX GTX980 Ti OC from the mini 6 pin headers. You just need the correct cable. As you can see from the prior posts I stress the GPU with a +500 MHz overclock. So far I have no failures and works just fine with no system shutdown. Another user here is having a shutdown issue when they hookup a 6 + 8 GPU. I think either the cables are incorrect or the PSU is old and needs to be replaced.

Here is some great information about computer power and how much you can use.

http://www.overclock.net/a/gpu-and-cpu-power-connections

 

[h9826790]

I think it's impossible to show the real reading in this case (because that 7.99A limit) of the mini 6pin unless we mod the circuit and capture the reading via the cable.

I expect running Furmark in macOS will just keep both mini 6pin cap at 7.99A (like my post above).

However, it will be much easier to calculate the estimate loading because we can now capture the

1) overall power consumption
2) CPU power consumption
3) memory power consumption
4) GPU power draw from the PCIe slot

Therefore, if we capture all the above data for both idle and during Furmark. We can have a rough idea how much current are the mini 6pins delivering. I expect the number would be around 120W. If the calculated number is around 150W. Then I will say even we still can't accurately prove that the mini 6pin able to deliver full 150W, but the real limit should not be too far from it (e.g. 140W) if we have the right cable.

 

[thornslack]

I still have some doubts regarding this. I own a flashed GTX 780 classified card (250watt also) for the occasional efi/boot screen needs, and it is a dual 8-pin card that was connected with mini-6 to 8-pins. I was able to overclock it but it would still trigger shutdowns prior to reaching its maximum stable overclock when using an external power supply. I don't believe it's due to an 'aging power supply, but as so many others have documented drawing too much load on traces.

 

[pastrychef]

I think it's impossible to show the real reading in this case (because that 7.99A limit) of the mini 6pin unless we mod the circuit and capture the reading via the cable.

I expect running Furmark in macOS will just keep both mini 6pin cap at 7.99A (like my post above).

However, it will be much easier to calculate the estimate loading because we can now capture the

1) overall power consumption
2) CPU power consumption
3) memory power consumption
4) GPU power draw from the PCIe slot

Therefore, if we capture all the above data for both idle and during Furmark. We can have a rough idea how much current are the mini 6pins delivering. I expect the number would be around 120W. If the calculated number is around 150W. Then I will say even we still can't accurately prove that the mini 6pin able to deliver full 150W, but the real limit should not be too far from it (e.g. 140W) if we have the right cable.

My theory is that it is giving you readings from pins 1 and 3. Hence, you top out at 7.99A. That equates to 96W or 48W per pin. If we assume that power draw is equal among all three pins, that would be 144W max from an 8 pin connection.

 

[h9826790]

My theory is that it is giving you readings from pins 1 and 3. Hence, you top out at 7.99A. That equates to 96W or 48W per pin. If we assume that power draw is equal among all three pins, that would be 144W max from an 8 pin connection.

Possible, in fact, not hard to test, but we will need some correct cables.

e.g. if anyone know how to make / mod this cables

1) Run some power consumption test with a simple setup (any 6pin's card will do. e.g. a 6+6pin 7950)

2) Record the power delivered by the mini 6pins.

3) Swap the mini 6pin's pin 2 / pin 3 wires (DO NOT mod the normal 6pin side, just mod the mini 6pin side)

4) run the test again

If the pin 2 power consumption is ignored by the software, and the power draw is balance between pin 1 and 3 (on the card side). Then we will see about 50% drop on the power consumption, because the card's pin 3 now is drawing power from the mini 6 pin 2 and cannot be show on the software.

P.S. anyone know how to mod these cables? I have few mini 6pin cable laying around. Can I just pull (hard) to get the pin out? Or I have to cut the cable (which I want to avoid)?

P.P.S. just found the video on youtube about how to remove the pin from the connector

 

[syops]

Reference to overclock.net link

http://www.overclock.net/a/gpu-and-cpu-power-connections

and

http://www.powerstream.com/Wire_Size.htm

Looks like from these two sources a single 18 gauge wire will handle 16 AMPS. A Molex-8981 connector is rated for
18 AWG – 08 AMPS – 96 watts. I think shorting a trace, plug or wire is the least of our concerns. But don't overload a PCIE with only 2 connected power pins. But please comment on this.

A good observation from the overclock.net link is their opinion of the true amount of power from the PSU to 6 and 8 pin PCIE AUX. "If there is any combos that are not covered, each 6 pin connector adds 80 watts, and each 8 pin connector adds 120 watts." This is falling in line with what h9826790 is saying. The power limits of both 8 and 6 PCIe AUX are the same. 2 connected power pins is 80 watts, three connected power pins 120 watts. Hmmm. What happened to the 150 from the 8 pin PCIe AUX? I think because the wiring can support a higher load, the 6+2 and 8 pin just pulls additional current. That is if you power supply can support it. A good Mac Pro PSU can.

Quote from the following link. "The PCI Express 2.0 specification released in January 2007 added an 8 pin PCI Express power cable. It's just an 8 pin version of the 6 Pin PCI Express power cable. Both are primarily used to provide supplemental power to video cards. The older 6 pin version officially provides a maximum of 75 watts (although unofficially it can usually provide much more) whereas the new 8 pin version provides a maximum of 150 watts."

http://www.playtool.com/pages/psuconnectors/connectors.html#pciexpress8

Quote from the following link. "The 6 pin to 8 pin PCI Express adapter will only work if the 6 pin PCI Express connector has a +12 volt wire at pin 2; although most good power supplies have this, the ATX standard is for it not to be there."

http://www.overclock.net/a/gpu-and-cpu-power-connections

 

[thornslack]

How would one determine if they have your theorized proper mini-six pin to eight-pin cables that have all three power pins properly connected? I have six to eight pin cables but by your rationale they wouldn't even power my 780 or TX if they weren't juiced up properly. And yet I like so many have hard shut downs if I draw too much over them. Or am I missing something?

 

[Surrat]

All this stress over power pins, and amp overload on the logic board traces really makes me glad I did the Pixlas mod to my 5,1's power supply !

I'm not using the logic board power sockets at all, and my TitanXp has its 6+8 bridged together into a single max power 6pin thats wired directly to the PSU's 980 watt 12v rail. I have no problems at any load test, and no power offs.

 

[TzunamiOSX]

The pin 2 is not for providing 150 Watt. The 2 extra pins tell the GPU: This connection supports up to 150 Watt.

Pin 2 is used to reduce the voltage drop if someone is using longer cables.

 

[Prince134]

This is very informative thread, but none of these theory or even 100% experimentally understood now IMO can free your mind to use the on board dual 6 pin cable. However we Know 980W is more than capable. The solution for using these two power source is the EVGA power link as described in the other thread in the post #4:

https://forums.macrumors.com/threads/ultimate-mac-pro-5-1-mod-for-triple-titan-x.2043646/

Take a close look at the picture, pin 2 is enabled, ie, it's not more than just a pair of 12V wires sending power to the 6+8.

The 6+8 power was a puzzle to me but not until I bought one of the $9.99 EVGA power link for myself. I laughed, really, at the moment when I took the plastic case off. That was it!!. By using it your two 6 pin can all work together balanced. It still can trigger shut down but chance reduced (we know it work with one Titan xP without issue).

Yes the ultimate solution is the Pixlas one or if you, like me, liking soldering, a pair of 12V+GND directly from PSU. All done, still have 3 empty SATA ports on board. Two Titan X, fully loaded. I think soldering is safer to provide better contact. But if you don't do soldering, and one Titan X is more than enough for most of your needs, that's easier fix.

I am also happy with the extra 175W from xbox one PSU for the 3rd GPU. Now 3 Titan X working. Cosmetically it's the same as one without modification. It's a powerful machine. All come from the Mac Pro 4/5,1 design's philosophy. None of PC or Hackintosh design can make it with style as it.

 

[EddieK420]

The Mac Pro 4,1 & 5,1 have plenty of PCIe AUX power, unless you need more than 300 watts for your GPU(s). Remember you get 75 watts from the PCIe slot. Each PCIe AUX 6 pin connector in the Mac Pro towers delivers 150 watts. Yes all three power pins in both of the PCIe AUX plugs are connected. The PCIe specifications don't required pin number two to have power, but it also does not prohibit it either. In the MAC Pro 4,1 / 5,1 it is connected. To be clear, this delivers the same power as a 8 pin connector without the extra sense and grounding pin on the 8 pin plug. Just buy the correct 6 to 8 Pin PCIe AUX cables and you are all set. I'm running a NVIDIA STRIX 980 Ti OC with two 8 pin plugs (150w + 150w + 75w = 375w). The Mac Pro 900+ watt power supply can handle it. I also have two 130 watt x5690s. No issues during stress testing. Need more power... Cut the plug off the apple power supply and terminate it with the standard ATX connectors.. Then you can run additional power from a new replacement power supply of your choice.

Make an intelligent choice. If you use something more, it should wear out sooner. Some of these machines are 7 years old and taxing a 7 year old power supply can cause it to reset or become inoperative.

Here is some great information about computer power and how much you can use.

http://www.overclock.net/a/gpu-and-cpu-power-connections

Hey guys. I have to disagree with this right here. I have a 250W GPU and my Mac is shuttind down. I am experiencing shutdowns on my Nvidia GTX 1080 Ti. Its a 250W GPU. I have a Mac Pro 2009 4,1 firmware upgraded to 5,1.

My 2009 Mac Pro shuts down immediately when running my 1080Ti in CUDA-Z in Heavy Load Test. My Mac Pro is 12-core 3.05 Ghz xeons.

I am using both power cables mini6pin to 8pin and mini6pin to 6pin connected to the 1080Ti. My 1080Ti is the founders edition made by Nvidia bought from their site.

Could my power cables be bad? Power cables look rather thin. I had a GTX 980 in there before with no issues. On the other pci slots I have an OWC accelsior card and a usb3 inatek card. Please help me

Just to provide complete information here are the specs:
2x 6-core 3.05Ghz Xeon processors
32 GB Ram
Nvidia GTX 1080Ti
Apple Superdrive and LG BluRay
1x Sata SSD
2x 3.5" Hard Drives
1 PCIe SSD
1 PCIe Inatek USB3 card

At this point I am thinking about doing the Pixlas mod. Any suggestions on this fellas?? I thought the Nvidia GTX 1080Ti was supposed to be able to run without external power on this mac pro. many thanks!

 

[Prince134]

Cable can be problematic when I do the 3 Titan X mod. When I first got the xbox 360 175W power supply I did not cut the wire and solder the wire to the 8+6 pin arrangement. Because it has the socket, and it's not ordinary socket, so I kind of just make 6 spiral copper wire inserted into the 3 12v and 3 GND pin slot of the socket to the pcie connectors and test it. It's not stable in that way. It would shot down and some times black screen. So the hardness do affect the power supply here. I'd say Pascal is a little bit more sensitive (hard to describe it) to little voltage change. You can tell some times the shot off at event not even begin any heavy load. With the theory in mind. I than cut the wire solder it to connectors (don't use the socket to test any more). It is resolved with soldering. Never shot off again.

Back to your physical issue, let's say your cable is fine but you have to understand another discussion here is that Mac Pro 5.1 although has enough 250W to the 1080 Ti from the 980W PSU, yes from the two 6pin as well, but individual 6pin + another individual 6pin is in doubt to not to trigger shot off on the board which is individually sensed. To avoid that, pixlas mod is one, or like me solder a pair of 12V +GND on the Main PSU. For you, only one 1080TI should be no issue unless something unusual exists, but you may take a look at the description of the EVGA power link (check some photo from the thread for understanding).

see #4
https://forums.macrumors.com/threads/ultimate-mac-pro-5-1-mod-for-triple-titan-x.2043646/


This device will internally balance/bridge both 6 pin together into your 1080 Ti. This is different from if you just plug 6>8, and 6>6 into your card. When I bought it was $9.99. now $29. But if you can go to local Fry's maybe you can make quick purchase and test it. I think this can be your first thing to try before you do the Pixlas mode, if you think cable is probably the reason. And let us know.

 

[EddieK420]

Cable can be problematic when I do the 3 Titan X mod. When I first got the xbox 360 175W power supply I did not cut the wire and solder the wire to the 8+6 pin arrangement. Because it has the socket, and it's not ordinary socket, so I kind of just make 6 spiral copper wire inserted into the 3 12v and 3 GND pin slot of the socket to the pcie connectors and test it. It's not stable in that way. It would shot down and some times black screen. So the hardness do affect the power supply here. I'd say Pascal is a little bit more sensitive (hard to describe it) to little voltage change. You can tell some times the shot off at event not even begin any heavy load. With the theory in mind. I than cut the wire solder it to connectors (don't use the socket to test any more). It is resolved with soldering. Never shot off again.

Back to your physical issue, let's say your cable is fine but you have to understand another discussion here is that Mac Pro 5.1 although has enough 250W to the 1080 Ti from the 980W PSU, yes from the two 6pin as well, but individual 6pin + another individual 6pin is in doubt to not to trigger shot off on the board which is individually sensed. To avoid that, pixlas mod is one, or like me solder a pair of 12V +GND on the Main PSU. For you, only one 1080TI should be no issue unless something unusual exists, but you may take a look at the description of the EVGA power link (check some photo from the thread for understanding).

see #4
https://forums.macrumors.com/threads/ultimate-mac-pro-5-1-mod-for-triple-titan-x.2043646/


This device will internally balance/bridge both 6 pin together into your 1080 Ti. This is different from if you just plug 6>8, and 6>6 into your card. When I bought it was $9.99. now $29. But if you can go to local Fry's maybe you can make quick purchase and test it. I think this can be your first thing to try before you do the Pixlas mode, if you think cable is probably the reason. And let us know.

Hey Prince. Thanks a lot for your response! I was reading a detailed consumption report for the GTX 1080Ti here:

https://www.pcper.com/reviews/Graph...-Ti-Review/Detailed-Power-Consumption-Testing

It says that it pulls 150W from the 8Pin and 70W from the 6Pin. So I believe you might be right. It might be pulling too much from 1 power connector and shutting down. Each AUX mini 6pin is supposed to be 75W right? So it's pulling too much from 1 side (8Pin) and not enough from the other(6Pin).

So are you sure the EVGA Powerlink thing will balance that out? So it pulls the same power from each aux power connector? If it does balance the power it pulls then I guess I will buy that and avoid doing the Pixlas mod for now. Thanks!

 

[h9826790]

Hey Prince. Thanks a lot for your response! I was reading a detailed consumption report for the GTX 1080Ti here:

https://www.pcper.com/reviews/Graph...-Ti-Review/Detailed-Power-Consumption-Testing

It says that it pulls 150W from the 8Pin and 70W from the 6Pin. So I believe you might be right. It might be pulling too much from 1 power connector and shutting down. Each AUX mini 6pin is supposed to be 75W right? So it's pulling too much from 1 side (8Pin) and not enough from the other(6Pin).

So are you sure the EVGA Powerlink thing will balance that out? So it pulls the same power from each aux power connector? If it does balance the power it pulls then I guess I will buy that and avoid doing the Pixlas mod for now. Thanks!

Yes, the 6pin officially rated up to 75W. But on cMP, it's able to deliver up to around 120W. So as long as you can balance the power draw. 220W totally is not a problem for the 2x mini 6pin.

Powerlink seems the best way to do it because it can share the load down to each pin. However, another simple method like 2x mini 6pin -> single 8pin -> 2x (6+2)pin should also work.

 

[EddieK420]

Yes, the 6pin officially rated up to 75W. But on cMP, it's able to deliver up to around 120W. So as long as you can balance the power draw. 220W totally is not a problem for the 2x mini 6pin.

Powerlink seems the best way to do it because it can share the load down to each pin. However, another simple method like 2x mini 6pin -> single 8pin -> 2x (6+2)pin should also work.

Thanks for your response. I guess I will pull the trigger on the EVGA Powerlink since it should balance the power out right?

However if I instead do the dual mini 6-pin to 8-pin I will still need another 6-pin power for the 1080Ti. It requires 1 8-pin and 1 6-pin the power this GPU.

 

[TzunamiOSX]

Here my Titan X (Maxwell) with an EVGA Powerlink. A good chance that the Powerlink can help you.

Furmark

The distribution was around 1.85:1 before the Powerlink

 

[h9826790]

Thanks for your response. I guess I will pull the trigger on the EVGA Powerlink since it should balance the power out right?

However if I instead do the dual mini 6-pin to 8-pin I will still need another 6-pin power for the 1080Ti. It requires 1 8-pin and 1 6-pin the power this GPU.

I mean dual mini 6 -> 8pin, AND a 8pin (female) -> DUAL 6+2 pin. Which means use the 8pin as a bridge (like what the Powerlink does to share the load), and allows you to power BOTH 8 pin and 6pin from the mini 6pin ONLY.
[doublepost=1493954407][/doublepost]

Here my Titan X (Maxwell) with an EVGA Powerlink. A good chance that the Powerlink can help you.

Furmark
View attachment 698495

The distribution was around 1.85:1 before the Powerlink

View attachment 698496

For your info, that reading is limited to 7.99A (4,1 and 5,1). If you see that reading during Furmark, most likely it occasionally draw > 100W from that particular boost cable. That's why regardless if you use the Powerlink or not, it never shows >8A, but simply shutdown the Mac if the 8pin draws too much.

 

[TzunamiOSX]

For your info, that reading is limited to 7.99A (4,1 and 5,1). If you see that reading during Furmark, most likely it occasionally draw > 100W from that particular boost cable. That's why regardless if you use the Powerlink or not, it never shows >8A, but simply shutdown the Mac if the 8pin draws too much.

I know about that 7,99 limit, but you can interpolate with the datas from idle and medium loads.

 

[Prince134]

Here my Titan X (Maxwell) with an EVGA Powerlink. A good chance that the Powerlink can help you.

Furmark
View attachment 698495

The distribution was around 1.85:1 before the Powerlink

View attachment 698496

Your picture worth thousands words.

 

[TzunamiOSX]

Your picture worth thousands words.

Yes, and thx for your posts about the Powerlink