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Alternatives for GPU power supply

casque

casque

macrumors newbie
Original poster
Apr 1, 2018
9
4
Europe
Hi everybody,

as a long time avid reader - I decided to start my first thread.

I have been looking far and wide (all around Germany) to find a solution to power my new RX 580 8GB in my 4.1 -> 5.1 Mac Pro.

I am well aware that there are cables offered on amazon.com - on websites based in the US or UK as well as China - that can do the job. Problem is: To receive the correct "dual mini 6pin to 8pin PCIe cable" I would have to wait at least a week if not several weeks until the cable arrives in Berlin - which is not really possible because of my current projects deadline. Unfortunately I need a solution asap.

Here my questions:
a) Does anyone here have experience with powering a GPU through SATA slots (option 1) ?
b) What about combining several adapter cables to run a GPU. Is that as good as one cable or is there possibly any danger involved (option 2) ?
c) what about AWG numbers. I see that the cables everybody recommends have 16AWG. The ones I can get here have 18AWG - so they are quite a bit smaller in diameter. Its that something to worry about?

Option 1:
(I could buy one like this in a local store - fastest solution)
8pin PCIe to dual SATA
-> Link 1

Option 2:
(I could order these three online in different online stores within Germany - 2nd fastest solution)
8pin PCIe male to dual 6pin female
-> Link 2
2x 6pin male to mini 6pin male
-> Link 3

What would you recommend ? Any thoughts on this would be highly appreciated.

Thanks a lot in advance !
 
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Thanks for the tip. Unfortunately I don't have PSU lying around so I might have to go with one of the other options.
 
If you are in the middle of a project, what is your current gpu....can you not continue to use it for the project.
My cable was ordered from china, delivered within about 7 days (estimate was a couple of weeks).
Whichever alternate option you go for, by the time you purchase what you need, your cable will probably arrive.
 
MarkC426 said:
If you are in the middle of a project, what is your current gpu....can you not continue to use it for the project.
My cable was ordered from china, delivered within about 7 days (estimate was a couple of weeks).
Whichever alternate option you go for, by the time you purchase what you need, your cable will probably arrive.
Click to expand...

It is not my primary system I want to update - but a second workstation I snatched a while ago. Originally got it as a spare - but since we are a bit behind schedule, I thought I put it to work after all, slap in the RX580 and do some effects heavy AE stuff parallel to the editing. As we have to work all weekend anyways - then at least get the most out of it ;-)
[doublepost=1531246145][/doublepost]
h9826790 said:
Option 2 is fine (it’s actually a very proper way to power a single 8pin GPU)

Option 1 is way outside limit, may kill the SATA ports.
Click to expand...

Ok - great - thanks for the reply. Then I will go with option 2.

Do you have any thoughts on the AWG numbers - you think that it is of any relevance ? I just ordered the three cables and it is the Y cable that has 18AWG - the other two have 16AWG.

You think this can cause any problems ? Is this a possible bottleneck under voltage of possibly full load during hours of heavy rendering ?
 
casque said:
It is not my primary system I want to update - but a second workstation I snatched a while ago. Originally got it as a spare - but since we are a bit behind schedule, I thought I put it to work after all, slap in the RX580 and do some effects heavy AE stuff parallel to the editing. As we have to work all weekend anyways - then at least get the most out of it ;-)
[doublepost=1531246145][/doublepost]

Ok - great - thanks for the reply. Then I will go with option 2.

Do you have any thoughts on the AWG numbers - you think that it is of any relevance ? I just ordered the three cables and it is the Y cable that has 18AWG - the other two have 16AWG.

You think this can cause any problems ? Is this a possible bottleneck under voltage of possibly full load during hours of heavy rendering ?
Click to expand...

For 8pin cable, there are three 12V wires. So, each of them only need to handle 50W. That means about 4A.

18AWG cable can easily handle 10A without any issue. In extreme case, it should able to handle ~80A for about 10s.

If there are 80A in the cable, I think the cable itself is the very last thing you will worry about.
 
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h9826790 said:
For 8pin cable, there are three 12V wires. So, each of them only need to handle 50W. That means about 4A.

18AWG cable can easily handle 10A without any issue. In extreme case, it should able to handle ~80A for about 10s.

If there are 80A in the cable, I think the cable itself is the very last thing you will worry about.
Click to expand...

Thanks a lot for clearing this up !

Seems like I am all set up then - cables should arrive tomorrow - latest day after that.

Great first thread - everything solved in a few hours.
 
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MarkC426 said:
Just to confirm....you are on Sierra or later also :)
This is required to use an RX580.
Click to expand...

Jup - for now I threw in an old Anglebird SSD I had lying unused and installed High Sierra on it - so should be fine.

But thanks for mentioning :)
 
I got the cable from the supplier in China also, but was scared about the long delivery time, but it ended up on my door in just under two weeks. I wouldn't stress about the delivery time IMO
 
iGobbleoff said:
I got the cable from the supplier in China also, but was scared about the long delivery time, but it ended up on my door in just under two weeks. I wouldn't stress about the delivery time IMO
Click to expand...

Well... if I wouldn't be stressed to begin with, I wouldn't have stressed about all this in the first place... and I guess I wouldn't have started my first thread here... and that would have been a pitty, wouldn't it ? ;)

The thing is that I need the GPU running by this Friday - which is three days from now. Even with high priority express shipping from China (which would probably costs 80 US dollars) the cable might not arrive in time.
 
Last edited:
casque said:
Well... if I wouldn't be stressed to begin with, I wouldn't have stressed about all this in the first place... and I guess I wouldn't have started my first thread here... and that would have been a pitty, wouldn't it ? ;-)

The thing is that I need the GPU running by this Friday - which is three days from now. Even with high priority express shipping from China (which would probably costs 80 US dollars) the cable might not arrive in time.
Click to expand...

If it is that urgent you can always go purchase an ATX power supply (should be widely available in Germany, otherwise Amazon Prime to the rescue) to power your card. It's an "ugly" solution but guaranteed to give the card enough power and not fry anything inside your Mac Pro. No need to stress!
 
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bookemdano said:
If it is that urgent you can always go purchase an ATX power supply (should be widely available in Germany, otherwise Amazon Prime to the rescue) to power your card. It's an "ugly" solution but guaranteed to give the card enough power and not fry anything inside your Mac Pro. No need to stress!
Click to expand...

Yeah - I know. Stress level is under control. Was just joking about myself. It's important not to take yourself too serious when the pressure amps up.

But the PSU will for sure be my last resort on Friday - if the cables don't arrive till then. Then I'll pick one up locally, in the mod store around the corner.
 
If you use a PSU you should also Google " The paperclip trick" = to make the PSU " turn on " you use a paperclip to SHORT pins 3 & 4. Also, make sure that the PSU has an 8 pin PCIe socket and cable. ( 6 pin can be run from two SATA to 6 pin if needed. )
 
Cables arrived in time. I have to add that the solution (option 2) feels totally save and high quality - so no need to order and wait for a special cable from China if you can get your hands on two mini 6pin to 6pin cables locally. The 8pin to dual 6pin should be the least problem to find.

I installed the RX580 yesterday in 5minutes or less and everything works perfectly. And I really mean PERFECTLY !

The system is super stable and handles Adobe tasks with ease. I'm in love :rolleyes:

Thanks again to everybody for the help !
 
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