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cMP 5,1 1080Ti Power Issues

K

killaninja58

macrumors newbie
Original poster
May 25, 2018
17
2
Hi guy's/gal's!

I've got a major problem whenever my 1080Ti FE (flashed for boot screen) hits heavy load and the whole mac just shut's off! This has only started happening recently but I haven't had the card long and I have set it up the way that I was told to when I bought it. with the 2 mini 6 pin connectors to the 8 pin and ta sata to 6 pin on the GPU.

I was wondering if
1) Doing the Pixlas Mod would work and if so how much of a pain is it/can it be? And how long will it take?
2) I've also been looking down the route of a seperate PSU in the optical bay but what would I be able to do about the spare sata connection (Kinda want it for a spare 1TB HDD if I need to

If someone with the knowledge that I clearly don't have could help then that would be grand!
 
J

joot

macrumors regular
Nov 3, 2006
110
21
That card uses a lot of power. I would get an external PSU and power it...
 
K

killaninja58

macrumors newbie
Original poster
May 25, 2018
17
2
Cheer's for the reply, What would you suggest me doing? the aux psu in the optical bay or using an external PSU entirely?
 
h9826790

h9826790

macrumors P6
Apr 3, 2014
16,656
8,584
Hong Kong
1) Single SATA to single 6pin is WRONG config. Each SATA only rated up to 55W, but 6pin can pull 75.

2) check if both mini 6pin are supplying power (e.g. via iStat)

3) my 1080Ti can work perfectly with “DUAL mini 6pin to single 6pin” + single 6pin FEMALE to dual 6+2pin” cables combination. You may consider that.

4) Pixlas mod is easy, follow this guide, and the whole process can be finished within an hour.

http://thehouseofmoth.com/mac-pro-pixlas-mod/
 
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K

killaninja58

macrumors newbie
Original poster
May 25, 2018
17
2
h9826790 said:
1) Single SATA to single 6pin is WRONG config. Each SATA only rated up to 55W, but 6pin can pull 75.

2) check if both mini 6pin are supplying power (e.g. via iStat)

3) my 1080Ti can work perfectly with “DUAL mini 6pin to single 6pin” + single 6pin FEMALE to dual 6+2pin” cables combination. You may consider that.

4) Pixlas mod is easy, follow this guide, and the whole process can be finished within an hour.

http://thehouseofmoth.com/mac-pro-pixlas-mod/
Click to expand...
So is that 2 mini 6 pins -> 6 pin male -> 6 pin female -> 6 +2 pin male (8 pins)?
If you could take a picture of your setup for me if I still don't understand?
 
h9826790

h9826790

macrumors P6
Apr 3, 2014
16,656
8,584
Hong Kong
Last edited:
K

killaninja58

macrumors newbie
Original poster
May 25, 2018
17
2
h9826790 said:
The picture is here.

https://forums.macrumors.com/thread...inity-6-on-mac-pro-1-1.2105403/#post-25801466

And the power draw test is here

https://forums.macrumors.com/threads/interesting-power-draw-observations.2116548/
Click to expand...
I've got a externalmpsu on the way.... But it's now infuriating me even more as every time I go to load EITHER W10 Pro or Mac is it just cuts out and shuts down.... So it's not under load.... But it just shuts off.... Any ideas? If not anyone that you may know?
 
h9826790

h9826790

macrumors P6
Apr 3, 2014
16,656
8,584
Hong Kong
killaninja58 said:
I've got a externalmpsu on the way.... But it's now infuriating me even more as every time I go to load EITHER W10 Pro or Mac is it just cuts out and shuts down.... So it's not under load.... But it just shuts off.... Any ideas? If not anyone that you may know?
Click to expand...

You still using a single SATA to power the 6pin?
 
K

killaninja58

macrumors newbie
Original poster
May 25, 2018
17
2
Having said that..... I switched out the cables I already had to still using the SATA to 6 pin but now a dual mini 6 pin -> 8 pin instead of SATA -
h9826790 said:
You still using a single SATA to power the 6pin?
Click to expand...
I was. But I've spoken to he seller and got a return happening hopefully for a replacement.... By which time I should have the external psu
 
h9826790

h9826790

macrumors P6
Apr 3, 2014
16,656
8,584
Hong Kong
killaninja58 said:
Having said that..... I switched out the cables I already had to still using the SATA to 6 pin but now a dual mini 6 pin -> 8 pin instead of SATA -

I was. But I've spoken to he seller and got a return happening hopefully for a replacement.... By which time I should have the external psu
Click to expand...

Sorry, I am a bit confused.

I understand that you have dual mini 6pin -> single 8pin, but how you power the 6pin now?
 
K

killaninja58

macrumors newbie
Original poster
May 25, 2018
17
2
h9826790 said:
Sorry, I am a bit confused.

I understand that you have dual mini 6pin -> single 8pin, but how you power the 6pin now?
Click to expand...
The same as I was before hand where macvidcards gave me the cables to power it that way. Which is why I'm confused, but I did order the PSU off of eBay but it's coming from USA hence why I haven't got that hooked up yet
 
h9826790

h9826790

macrumors P6
Apr 3, 2014
16,656
8,584
Hong Kong
killaninja58 said:
The same as I was before hand where macvidcards gave me the cables to power it that way. Which is why I'm confused, but I did order the PSU off of eBay but it's coming from USA hence why I haven't got that hooked up yet
Click to expand...

I see. Than may be overloading the SATA port is the issue.

Each card / GPU's power draw characteristic has tiny difference (even for the exact same model), and we still has no idea at which point, the cMP will shut itself down if you draw too much from the SATA port. May be your card just draw a bit more than average. And even at boot / self test / or some simple task, the power spike just reach that point and able to shut the Mac down.

A GPU should draw more when it's warmer. And the temperature is getting warmer unless you are in the Southern Hemisphere. This may be the reason why this problem suddenly pops up.
 
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K

killaninja58

macrumors newbie
Original poster
May 25, 2018
17
2
h9826790 said:
I see. Than may be overloading the SATA port is the issue.

Each card / GPU's power draw characteristic has tiny difference (even for the exact same model), and we still has no idea at which point, the cMP will shut itself down if you draw too much from the SATA port. May be your card just draw a bit more than average. And even at boot / self test / or some simple task, the power spike just reach that point and able to shut the Mac down.

A GPU should draw more when it's warmer. And the temperature is getting warmer unless you are in the Southern Hemisphere. This may be the reason why this problem suddenly pops up.
Click to expand...
Hi,

Thanks for that now as much of a pain as I don't wanna be..... The card itself has doesn't it again even after I put it back in the nbida box for a good 10-12 hours.... XD but now it's just decided to boot up and stay as I was taking a video for MVC to show him what it does..... Bloody thing, but he thinks it's wrong drivers? Which would make sense (to me) if it was only happening in Mac os.... But it's happening in both? Which I'm a little confused about.... I guess the best thing is to keep in contact with MVC and just wait till the 5.25" PSU gets here haha
 
lilins

lilins

macrumors member
Apr 25, 2018
96
29
Villeurbanne
honestly, did the pixlas mod for a vega64 (4 sata bays populated, pcie slots 3 and 4 populated with usb3 card nd sonnet tempo ssd)no issue on power. it is not so much difficult operation, and the guide on the pixlas mod thread is complete ans easy to follow.
 
rivangom

rivangom

macrumors member
Aug 9, 2019
41
13
Amsterdam
With the Pixlas mod, can you splice with two cables in case you want to have two power hungry GPU’s? What do you do with the two mini 6-pin connectors on your motherboard? Can they still be used?

Seen these connectors and would that not make the cable splice easier?

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s.m.t.

s.m.t.

macrumors 6502
Mar 7, 2010
285
22
I did a variation of the mod and soldered directly to the PSU an 8pin socket to allow it to me modular. Would only suggest opening the PSU if you are comfortable working with high voltage electronics...
 
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