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

[h9826790]

no card, with load resistance
and the PSU shut down at 145W
with 10% headroom it is 130W
absolutly save is 120W

Standard 6pin rated 75W, which means all Apple approved HD4870, HD5870, HD7950, GTX680's 6pin can draw up to 75W from a mini 6pin. That 60W max doesn't make any sense at all.

Also, from my own power draw test, the cMP shut down at 120W from a SINGLE mini 6pin, not 2x mini 6pin.

I can keep the power draw at about 100W for each mini 6pin and nothing happen. I did that for years. Nothing burn.

[doublepost=1565248801][/doublepost]

I think you may be right because i did not have this issue with my RX 480 and my friend has the same machine as me and he is having the same issue with is NVIDIA GTX 560 which is powered with 150W. What do you recommend I do? Pixlas mod?

Doesn't make any sense, I can power 2x 7950 with just mini 6pins, no SATA power, no Pixlas mod

https://forums.macrumors.com/thread...mac-with-2-d700s.1732849/page-5#post-21722712

https://forums.macrumors.com/thread...or-approaching-silence.1982499/#post-23120938

I can also power a 1080Ti with just the mini 6pins

https://forums.macrumors.com/threads/getting-my-5-1-ready-for-vive-vr.2046670/page-3#post-25429070

How can a much lower TDP single GTX560 setup causing any issue. Dual mini 6pin is way more than enough to power a single GTX560.

 

[tommy chen]

maybe it was a faulty backplane or PSU back then.
this cMP had constant shutdowns with a GTX980ti

 

[adrianc7459]

Standard 6pin rated 75W, which means all Apple approved HD4870, HD5870, HD7950, GTX680's 6pin can draw up to 75W from a mini 6pin. That 60W max doesn't make any sense at all.

Also, from my own power draw test, the cMP shut down at 120W from a SINGLE mini 6pin, not 2x mini 6pin.

I can keep the power draw at about 100W for each mini 6pin and nothing happen. I did that for years. Nothing burn.
View attachment 852056
[doublepost=1565248801][/doublepost]

Doesn't make any sense, I can power 2x 7950 with just mini 6pins, no SATA power, no Pixlas mod

https://forums.macrumors.com/thread...mac-with-2-d700s.1732849/page-5#post-21722712

https://forums.macrumors.com/thread...or-approaching-silence.1982499/#post-23120938

I can also power a 1080Ti with just the mini 6pins

https://forums.macrumors.com/threads/getting-my-5-1-ready-for-vive-vr.2046670/page-3#post-25429070

How can a much lower TDP single GTX560 setup causing any issue. Dual mini 6pin is way more than enough to power a single GTX560.

How are you powering your 1080Ti? Are you just plugging it in and turning it on and it is able to power it, or are you doing some extra to force that amount of power to be pulled?

thanks

 

[h9826790]

How are you powering your 1080Ti? Are you just plugging it in and turning it on and it is able to power it, or are you doing some extra to force that amount of power to be pulled?

thanks

Dual mini 6pin -> single 6pin -> dual 6+2pin

This is the way I powered it.

No extra steps / mod.

I use the single 6pin as a bridge to evenly distributed the load between mini 6pins.

 

[adrianc7459]

Dual mini 6pin -> single 6pin -> dual 6+2pin

This is the way I powered it.

No extra steps / mod.

I use the single 6pin as a bridge to evenly distributed the load between mini 6pins.

Can you send a link to those cables. I cannot find them

 

[h9826790]

Can you send a link to those cables. I cannot find them

For your reference only. I got mine from China, which is a Chinese web page, I don't think that's good for you.

https://www.amazon.com/COMeap-Express-Video-Adapter-15-inch/dp/B07J336WY4

https://www.amazon.com/Express-Grap...9Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

[Macschrauber]

Dual mini 6pin -> single 6pin -> dual 6+2pin

Seems a typo here. Sure you meant Dual mini 6 to 8 pin plus 8 pin to Dual 6+2

 

[h9826790]

Seems a typo here. Sure you meant Dual mini 6 to 8 pin plus 8 pin to Dual 6+2

No typo, I use 6pin as bridge, not 8pin.

 

[HaypurTiryading]

Why don't you use Dual mini 6 pin male to single 8 pin female? Is it more safer than 6 pin?

Your cabling better explained: Dual mini 6pin male to single 6pin female -->> Dual, 6+2pin male to male

 

[startergo]

Why don't you use Dual mini 6 pin male to single 8 pin female? Is it more safer than 6 pin?

Your cabling better explained: Dual mini 6pin male to single 6pin female -->> Dual, 6+2pin male to male

I used the same setup. The idea is to spread the current flow equally from the 6mini pins to the 6 pin connector

 

[HaypurTiryading]

I used the same setup. The idea is to spread the current flow equally from the 6mini pins to the 6 pin connector

Ok. I understand the idea. Cables act like Evga Powerlink or reverse. But in extreme situations 200 watts( 2x mini 6pin, each 100watt) can pass through the 6 pin female connector. Isn't it dangerous? Why don't we use 8 pin? Maximum current capacity of 8 pin, should be double of 6 pin? Am I wrong?

 

[h9826790]

Why don't you use Dual mini 6 pin male to single 8 pin female? Is it more safer than 6 pin?

Your cabling better explained: Dual mini 6pin male to single 6pin female -->> Dual, 6+2pin male to male

It won't be safer, still only pin 1,2,3 are powered.

6Pin

8pin

Ok. I understand the idea. Cables act like Evga Powerlink or reverse. But in extreme situations 200 watts( 2x mini 6pin, each 100watt) can pass through the 6 pin female connector. Isn't it dangerous? Why don't we use 8 pin? Maximum current capacity of 8 pin, should be double of 6 pin? Am I wrong?

As per PCIe standard (PCI Express®225 W/300 W High Power Card Electromechanical Specification Revision 1.0RC), each pin should able to handle at least 7A

Which mean 84W per pin (absolutely minimum, with zero buffer). So, 3 x 84W = 252W.

In reality, before we reach 252W, the cMP should already shut itself down. And it is extremely rare that no buffer at all when manufacturing this kind of product.

 

[HaypurTiryading]

Thank you for detailed information. Now 6 pin make sense.

Last question: Your cabling method is universal for every card but Evga solution is card specific. As a result they do same thing?

I will change my cable setup.

 

[h9826790]

Thank you for detailed information. Now 6 pin make sense.

Last question: Your cabling method is universal for every card but Evga solution is card specific. As a result they do same thing?

I will change my cable setup.

EVGA PowerLink has build-in capacitors, that will smooth out the power spike.

Simply using 6 or 8pin as bridge can only evenly distribute the loading.

 

[Supersoberguy]

For your reference only. I got mine from China, which is a Chinese web page, I don't think that's good for you.

https://www.amazon.com/COMeap-Express-Video-Adapter-15-inch/dp/B07J336WY4

https://www.amazon.com/Express-Graphics-Splitter-Extension-TeamProfitcom/dp/B077WRCZWD/ref=sr_1_1_sspa?keywords=8pin+female+to+dual+6+2&qid=1565348258&s=electronics&sr=1-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExMUQ1QUc1RFE0Q0FNJmVuY3J5cHRlZElkPUEwNTY3MDAzMzQxM1JMQ1QxM0JLWCZlbmNyeXB0ZWRBZElkPUEwMTcxODcxM0hPWlAyM0pYWkhLRCZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

Dear h9826790, you sent the link to dual mini 6 pin to 8 pin, even though you explicitly say that dual mini 6 pin to 6 pin is needed.

I also did not find any links for this kind of cable on aliexpress or taobao. If you could be so kind to share these links in here, or privately as direct message. I am planning to power up the dual 8 pins GPU as per your scheme.

Kind regards.

 

[bulgakov]

I had a 4,1 flashed to 5,1 .. I put in a Sapphire RX 570 with one 6 to 8 pin. Supposedly this is a 168 watt card. the machine had a lot of hours on it from me and previously the university. the PSU and logic board blew. Gathering from what I read I may have overpowered things and maybe trace on board went. I am getting a MP 5,1 and will use the dual 6 to 8 route this time. Until PSU blew i saw no interruptions or slow downs . PSU died and machine went down. Then it almost worked a number of times. Any suggestions ?

 

[HaypurTiryading]

I had a 4,1 flashed to 5,1 .. I put in a Sapphire RX 570 with one 6 to 8 pin. Supposedly this is a 168 watt card. the machine had a lot of hours on it from me and previously the university. the PSU and logic board blew. Gathering from what I read I may have overpowered things and maybe trace on board went. I am getting a MP 5,1 and will use the dual 6 to 8 route this time. Until PSU blew i saw no interruptions or slow downs . PSU died and machine went down. Then it almost worked a number of times. Any suggestions ?

Use @h9826790 s method (read up, discussed closely) or use Evga PowerLink if it fits. Also power saver bios switch (if tha card has) can help lower the load.

 

[bulgakov]

Use @h9826790 s method (read up, discussed closely) or use Evga PowerLink if it fits. Also power saver bios switch (if tha card has) can help lower the load.

Thanks ..i think mine does have that switch.. I have seen many installation videos of cards that drew more power but until i found this thread I did not realize the dangers .. the sneaky part is tricky the 5,1 into accepting mojave .. At the time it was easy so i will have to go back and check.. I actually did it the first time with a gt120 from apple ..

 

[Executor]

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.

 

[MIKX]

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.

Your setup looks sooooooooo clean ! Well done. I use the EVGa PowerLink ( remotely ) too with an RX 580 but my internal case doesn't look as "neat" as yours.

 

[Executor]

Your setup looks sooooooooo clean ! Well done. I use the EVGa PowerLink ( remotely ) too with an RX 580 but my internal case doesn't look as "neat" as yours.

Thank you so much. I still need to clean it properly. Get new ram, USB3 card and new WiFi card. The Mac Pro 5,1 May be old but it is truly a timeless design.

 

[rivangom]

Can you do a double pixlas mod on one PSU? In case you would like to use two power hungry GPU. If yes, can you detail how the splice should be?

Many thanks!

 

[Executor]

Can you do a double pixlas mod on one PSU? In case you would like to use two power hungry GPU. If yes, can you detail how the splice should be?

Many thanks!

With the standard mod you can power two video cards that require 8 pin and six pin connections. That’s as far as I would go if I were you. But I am sure someone more knowledgeable than me will chime in if it’s possible.

 

[rivangom]

With the standard mod you can power two video cards that require 8 pin and six pin connections. That’s as far as I would go if I were you. But I am sure someone more knowledgeable than me will chime in if it’s possible.

Thanks and will follow your advice.

 

[Hdalio]

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