MP 1,1-5,1 NVidia GTX 780 (6GB) Power Draw Shuts Down MP 5,1

[kittonian]

I have a heavily upgraded MP 5,1 (12-Core 3.46Ghz with 64GB of 1333mhz RAM, a PCIe SSD Boot Drive, and all 4 Sata Bays populated with large hard drives) with a flashed NVidia GTX 780 (6GB) video card using display port to drive an ultra-wide LG monitor.

This system has been running fine for years now but yesterday I was using Twinmotion with the new grass and after painting a bunch of grass my computer suddenly turned off. I knew the GPU was being pushed a lot harder because I could hear it, and obviously too much power was being drawn and thus the system turned off.

I spent last night reading about this issue and right now I have a 6pin-8pin cable/adapter and a 6pin-6pin cable plugged in powering the card. I know I need to get a dual 6pin to 8pin adapter but I'm not sure where to draw enough power for the 6pin port on the card (optical drive that isn't being used?) and what cable to purchase. If I can help it, I would rather not have an external power supply just for this card as this is in an office where I see clients and it needs to be as quiet as possible.

 

[kittonian]

These are the two cables I am considering purchasing:

Dual 6pin to 8pin - https://www.amazon.com/gp/product/B07J336WY4/ref=ox_sc_act_title_1?smid=A3KOUHYUNS6C1J&psc=1

6pin to SATA Power - https://www.amazon.com/gp/product/B01EUSZ0BQ/ref=ox_sc_act_title_2?smid=AKXVBT49GGF3B&psc=1

The thought process is to connect both 6pin connections on the logic board to the dual 6pin to 8pin cable and use that to power the 8pin on the GPU. Then I would connect the 6pin to the GPU and the SATA Power to the connection currently being used to power the optical drive.

Just want to ensure that this will work AND that it will provide enough power to handle the NVidia GTX 780 (6GB) card if Twinmotion starts pushing it hard and it requires more power. Thanks!

 

[MIKX]

Use a dual SATA to one 6 pin for the 6 pin socket on the GPU.
( Neve use a SINGLE SATA to 8 pin )

DUAL Mini 6 pin to SINGLE 8 pin for the GPU 8 pin socket.

Better still buy an EVGa PowerLink - I use this on both a Sapphire ual-X 7970 & an MSI RX 580 ( at different times ) . the PowerLin smoothes out ALL the available power plugged into it then sends it to the GPU = no power spikes.

How to use the EVGa PowerLink

From post #1

EVGA PowerLink with AMD GPUs

Just got the EVGA PowerLink working with my Sapphire Dual-X 7970 3gb. IMPORTANT : The power input sockets on the PowerLink are 2 X 8 Pin female and cannot be changed. The EVGA PowerLink ensures that exact power demanded by a GPU is supplied. That said, one must still supply enough power to...

forums.macrumors.com

Amazon link https://www.amazon.com/EVGA-PowerLink-Support-Founders-600-PL-2816-LR/dp/B01MQ1YEYH

 

[kittonian]

Thank you for the response. Why would I need dual SATA to 6pin, and even if I bought that, where do I get the other SATA connector (there's only one for the optical drive that I will disconnect)?

The GTX 780 specs at 250W. The PCIe slot has 75W and each 6pin connector on the logic board has 75W, meaning with just the 8pin connected I have 225W going to the card. Then a single SATA connection gives me approx 54W.

Just trying to understand the why's and how's of this setup. I don't need overkill, I just need the system to not shut off when pushing Twinmotion to its limits with lots of grass and vegetation.

 

[Demigod Mac]

The EVGA PowerLink might resolve the shutdowns on its own. Inexpensive and worth a try.

When a power spike occurs it might be tugging too hard on the 6->8 pin (thinking it's a real 8 pin) and the Mac shuts down to protect itself. The PowerLink would shift some of the load over to the other 6 pin and together they might be able to handle the spike.

 

[kohlson]

@MIKX offers good advice. The cabling is not expensive, nor would I consider it overkill in your situation. 250w is more than the cMP was designed to support, so a little extra care isn't a bad thing.

Perhaps a long shot, but are you sure the 780 is not overheating and shutting off from that?

 

[kittonian]

The GTX 780 does not seem to be supported for use with the Powerlink

 

[Snow Tiger]

I have a heavily upgraded MP 5,1 (12-Core 3.46Ghz with 64GB of 1333mhz RAM, a PCIe SSD Boot Drive, and all 4 Sata Bays populated with large hard drives) with a flashed NVidia GTX 780 (6GB) video card using display port to drive an ultra-wide LG monitor.

This system has been running fine for years now but yesterday I was using Twinmotion with the new grass and after painting a bunch of grass my computer suddenly turned off. I knew the GPU was being pushed a lot harder because I could hear it, and obviously too much power was being drawn and thus the system turned off.

I spent last night reading about this issue and right now I have a 6pin-8pin cable/adapter and a 6pin-6pin cable plugged in powering the card. I know I need to get a dual 6pin to 8pin adapter but I'm not sure where to draw enough power for the 6pin port on the card (optical drive that isn't being used?) and what cable to purchase. If I can help it, I would rather not have an external power supply just for this card as this is in an office where I see clients and it needs to be as quiet as possible.

If your GTX 780 has one 6 pin and one 8 pin booster power connectors , then you might try this :

Dual mini 6 pin PCIe ( Mac logic board ) to standard 8 pin PCIe ( GPU ) splitter power cable . Will provide 150 W . The connection would like 150 W , so you are good here .

COMeap Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Cable for Mac Pro Tower/Power Mac G5 15-inch(38cm)

COMeap Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Cable for Mac Pro Tower/Power Mac G5 15-inch(38cm)

www.amazon.com

Dual SATA ( Mac HDD Bay backplane ) power to standard 6 pin PCIe ( GPU ) splitter power cable . Will provide 66 W . The connection would like 75 W , so we are a little shy . It should not be a problem . Connect to backplane HDD Bay 2 and 3 .

StarTech.com 6in SATA Power to 8 Pin PCI Express Video Card Power Cable Adapter - SATA to 8 pin PCIe power (SATPCIEX8ADP)

6IN DUAL SATA TO PCIE VIDEO

www.amazon.com

And should you require it , an 8 pin PCIe extension power cable .

JacobsParts 8-Inch 8 pin PCI Express PCI-E Power Extension Cable for Video Card

Extend the distance between a power supply and graphics card with this 8-pin PCI-Express power extension cable. 18 AWG copper wire ensures safe and reliable operation.

www.amazon.com

There is a caveat . If your other HDDs consume a lot of juice , this might not work . The backplane provides a total of ( unknown ) power across all four SATA connections . But I've had long term success pulling 33 W from each of two backplane connectors concurrently ( total of 66 W ) without burning out any traces .

By the way , the SATA Optical Disc Drive ( ODD ) Bay connectors are not used with this method .

 

[MIKX]

kittonian


( EDITED )

The EVGa PowerLink was expressly designed to be used with NVIDIa GPUs.

Granted, EVGa admits that the PowerLink does not fit ALL NVIDIa GPUS but the GTX 780 is basically the same as my Sapphire Dual-X 7970 3gb.; One 8 pin & one 6 pin socket except that the GTX 780's 8 pin & 6 pin socket positions are positioned oppositely with the hGTX 780 8 pin socket being at the end of the card. This is not a problem because the PowerLink's power sockets TO the 780 can be removed, adjusted and there is a spare 6 pin socket + an Allen Key in the Powerlink box.

Also to use the PowerLink with my AMD Sapphire Dual-X 7970 3gb I had to cut away a small section of the cooling fans shroud.

Now it fits perfectly.

I only use the EFI flashed 7970 when I need to have bootscreens. My current setup is using an MSI Armor RX 580 8gb with the PowerLink in ' bridge mode ' = the PowerLink sits on top of the cMP PCI compartment fan.


================================================
For the GPU 780 6 pin socket

1. Move two drives from your PCI compartment, mount them in the DVI Drive cage.

2. Now you will need a TWO x SATA to ONE x 6 pin cable.

Now read Post #1 here

EVGA PowerLink with AMD GPUs

Just got the EVGA PowerLink working with my Sapphire Dual-X 7970 3gb. IMPORTANT : The power input sockets on the PowerLink are 2 X 8 Pin female and cannot be changed. The EVGA PowerLink ensures that exact power demanded by a GPU is supplied. That said, one must still supply enough power to...

forums.macrumors.com

Go down to CABLING SETUP.

Read that part until you understand it.

( The PowerLink comes with a spare power OUT 6 pin socket - you will have to remove ONE of the PowerLink 8 pin sockets and replace it with this spare 6 pin socket - there is an Allen key included in the PowerLink box to use to accomplish this. )



=======================================================

If you still do not understand how to use the Powerlink with the GTX 780 tell us your EXACT current PowerLink cabling set up.

eg: Attach all the relevant cables to the PowerLink OUTSIDE your cMP - take some photos, post them here.

 

[w1z]

I was also using an EVGA Powerlink with my old EVGA GTX 780 6GB SC ACX and had no issues running furmark stress test.

You need to balance the power draw from the 2 mini 6-pins. You might also need to dedust and apply new thermal paste if the card is sounding louder than when you first started using it.

 

[MIKX]

EVGa Powerlink FAQ

EVGA FAQ - Which Graphics Cards are compatible with EVGA PowerLink?

EVGA North America's #1 NVIDIA partner.

www.evga.com

 

[MIKX]

I was also using an EVGA Powerlink with my old EVGA GTX 780 6GB SC ACX and had no issues running furmark stress test.

You need to balance the power draw from the 2 mini 6-pins. You might also need to dedust and apply new thermal paste if the card is sounding louder than when you first started using it.

I agree, TWO x SATA to ONE x 6 pin should be safe if used in conjunction with the TWO x Mini 6 pin to ONE x 8 pin for the GTX 780.

 

[w1z]

I agree, TWO x SATA to ONE x 6 pin should be safe if used in conjunction with the TWO x Mini 6 pin to ONE x 8 pin for the GTX 780.

The EVGA Powerlink was only powered by the 2 mini 6-pin power connectors using 2 x mini 6-pin to 6-pin cables. I never connected the powerlink to the sata power ports.

 

[MIKX]

Either will work, the Powerlink will just balance the available power to decrease power spikes.

 

[kittonian]

OK. Here's the plan. I am doing the dual 6pin to 8pin for the 8pin port off the logic board and a single SATA to 6pin connector for the 6pin using the optical drive's SATA connection (disconnecting the optical drive). If that works and solves the issue I'm all set. If not, the Powerlink is pretty cheap and I'll buy one of those (and maybe a dual SATA to 6pin at the same time). I'm just not sure where I would connect the second SATA connection as all my drive bays are in use.

 

[Snow Tiger]

OK. Here's the plan. I am doing the dual 6pin to 8pin for the 8pin port off the logic board and a single SATA to 6pin connector for the 6pin using the optical drive's SATA connection (disconnecting the optical drive). If that works and solves the issue I'm all set. If not, the Powerlink is pretty cheap and I'll buy one of those (and maybe a dual SATA to 6pin at the same time). I'm just not sure where I would connect the second SATA connection as all my drive bays are in use.

A single ODD SATA connection is not going to provide the 75 W a 6 pin PCIe booster connector on the GPU expects . No where even close . You need to work off the backplane and grab 33 W + 33 W from two SATA HDD Bay connectors . If your SATA HDD Bays must be occupied with HDDs , then an alternative is to use an external PSU and drill holes into the side access panel of your Mac .

 

[kittonian]

I am not going to drill holes in my machine. I will sell the video card before I do that. This card maxes out at 250W and with the PCIe and 8pin connector alone, that gives the card 225W. Technically, that means the 6pin power would only need to draw another 25W of power and the single SATA power connection provides 54W (at least from all my research) and may possibly be able to provide a bit more based on some people's measurements I have read.

Bear in mind that right now, this card has been running without issue for a few years with only a single 6pin to 8pin connector to the 8pin and a 6pin to 6pin for the 6pin connector off the two logic board ports. This new cable configuration should provide the card with quite a bit more power.

As I said, we'll see what happens. Either this works or I'll have to figure out the next steps.

 

[MIKX]

I am not going to drill holes in my machine. I will sell the video card before I do that. This card maxes out at 250W and with the PCIe and 8pin connector alone, that gives the card 225W. Technically, that means the 6pin power would only need to draw another 25W of power and the single SATA power connection provides 54W (at least from all my research) and may possibly be able to provide a bit more based on some people's measurements I have read.

Bear in mind that right now, this card has been running without issue for a few years with only a single 6pin to 8pin connector to the 8pin and a 6pin to 6pin for the 6pin connector off the two logic board ports. This new cable configuration should provide the card with quite a bit more power.

As I said, we'll see what happens. Either this works or I'll have to figure out the next steps.

For a start, the two 6 pin ports on the cMP motherboard are titled "Mini 6 pin". . not "6 pin ".

There is a vast difference between " Mini 6 pin" & " 6 pin".

=================================================

GTX 780 6 pin port

Don't use a SINGLE ( one ) SATA to 6 pin" cable.

For the GTX 780's 6 pin socket use a " TWO x SATA to ONE 6 Pin cable ".

This is the cable to use for the GTX 780 6 pin socket.

US$7.95 + shipping
Amazon.com weblink

J&D 6 Pin PCIe to Dual SATA Power Cable, 2X SATA to 6 Pin PCIe Express Graphics Video Card Power Cable Adapter (2 Pack), 8 Inch

J&D 6 Pin PCIe to Dual SATA Power Cable, 2X SATA to 6 Pin PCIe Express Graphics Video Card Power Cable Adapter (2 Pack), 8 Inch

www.amazon.com

===================================================

Look at the last entry, this is why you need to use a "DUAL SATA to 6 pin" cable for the GTX 780's 6 pin socket.

Do you feel confident in risking your Mac Pro's motherboard for $7.95 ?


​

 

[kittonian]

I am aware that the logic board has mini 6pin connectors. As I said, I already have this card in use, and I listed the correct dual mini 6pin to 8pin cable above in this thread.

I hear what you are saying about the dual SATA to 6pin cable and I understand the power requirements. However, and I have asked this quite a few times now in this thread, I do not know where I would plug-in the second SATA connection when I only have the optical drive to disconnect. Is there an additional SATA port I am unaware of that is open for this connection?

I still don't understand why my solution will absolutely not work. If I am under-powering the 8pin connection by half right now, and the card works for everything except the most demanding Twinmotion project, is it possible that the solution I presented would do what I need? I understand that it is not the best way to do things and if there is an additional SATA connection I can use, without disconnecting any of my hard drives, I am more than happy to purchase the dual SATA to 6pin cable.

I am not interested in purchasing an external power supply at this time, as the cost for the super quiet ones are around $150. If there is no other option, I am ready to sell this card and find a Radeon card that will perform as well or better than the GTX 780 so I can finally move off of High Sierra and upgrade to the latest OS. None of my software uses CUDA and I do not play games on this machine. I am using Archicad, Twinmotion, Cinema 4D and Vray.

 

[MIKX]

kittonian

Put TWO SATA drives in the DVI cage.
If you still need one more SATA port in the DVI cage, Google " Amazon.com SATA splitter cable."

I power my ASUS external DVI drive through an external 7 port USB powered HUB.

If you buy another card I recommend the Sapphire Pule RX 580 8gb. with the EVGa PowerLink

 

[kittonian]

OK, I don't have an issue with putting one of my drives in the optical bay (or even two of them for that matter), however wouldn't that still use the available SATA connections in the same way?

I did find the correct bracket to do this: https://eshop.macsales.com/item/Other World Computing/MM52T35MP9/

 

[MIKX]

The 4,1 & 5,1 cMPs have 6 SATA ports. 4 in the PCIe area and two in the DVI / PSU area.

Assuming the drives are SSD .. .you don't need a bracket. . just connect them, they can't fall out.

 

[kittonian]

If there are two SATA connections in the DVI area, why do I need to move a drive at all? Couldn't I just connect both to those? And, no, they are all large 3.5" drives, not SSDs. The only SSD is on a PCIe card (my boot drive).

 

[MIKX]

If there are two SATA connections in the DVI area, why do I need to move a drive at all? Couldn't I just connect both to those? And, no, they are all large 3.5" drives, not SSDs. The only SSD is on a PCIe card (my boot drive).

The reason to move SATA connected HDDs is tha tyou can then use a shorter SATA cables to power your GPU 6 pin cable. Didn't that occur to you ?

Look closely at the DVI cage . . . the holes on the sides match up with DVD drives . . . . . AND. 3.5" HDDs.

Mount the 3.5" drives in the DVD drive cage with the screws already attached to the DVD drive.

Learn more about your Mac Pro. 😇
[automerge]1578803996[/automerge]

 

[kittonian]

No need to be snarky. It was a valid question and I don't need to move a hard drive in order to use a shorter cable. I can just purchase a longer cable and then I don't have to move anything and I still get two SATA connections to power the the 6pin. Did that solution ever occur to you?

In fact, this was literally my very first question. We didn't need to go back and forth for 24 posts to get there. I appreciate your advice and your assistance, but don't you think you could have simply responded with, buy a dual SATA to 6pin cable and connect it to the two SATA ports in the DVI cage, bearing in mind that you will need a longer cable to do so?