Did you test it the way I recommended ? with external power from a PC next to the mac ? If that works then you must do the Pixlas mod, especially if its a vega64.
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
MP 1,1-5,1 MVC Vega 56 anyone ?
- Thread starter macguru9999
- Start date
- Sort by reaction score
May I know how you exactly power your card? (or what exactly config you tried before)
Using extra SATA ports or PowerLink may help, but only if you connect them correctly.
e.g. Even if you provide two extra SATA ports.
By numbers
1) PCIe slot rated up to 75W
2) each mini 6pins rated up to 75W (actual can do ~120W)
3) each SATA ports rated up to 55W
So, total rated power is 335W, should be OK to power a Vega 64 (I treat it as Vega 64 now, because it's with a Vega 64 ROM. Therefore, a Vega64 power draw).
However, it you do
A) Dual mini 6pin to 1st 8pin
B) Dual SATA to 2st 8pin.
This is a no go, because the 2nd 8pin may draw 150W, and 20W more than a SATA port can provide. In this case, shutdown protection may occur. (This is seems what you did)
So, how about 2x "mini 6pin + SATA -> 8pin"?
This won't work either, because when the 8pin try to draw 150W, the SATA port may still need to supply 75W.
And this is an interesting fact from Mr. Hossam Grees Saad.
Depends on how the wires actually connected inside the cables. The SATA port may deliver much less than you can expect.
e.g. In the above case, only one 12V pin is actually connected to the SATA port, and the mini 6pin still need to deliver ~120W to the 8pin under heavy load. If you have such cable combination. It may not good enough to prevent the force shutdown.
What you want is a 3:2 cable. So 60% from the mini 6pin (all three 12V pins connected), 40% from the SATA (only two 12V pins connected). However, I don't know how to find this cable except build one by myself.
If you can find this cable, the 2x "mini 6 + SATA -> single 8pin" may work.
On the other hand, TDP is just for thermal capacity calculation. Not really the card's power draw. Especially TDP cannot reflect the power spike. A Vega64's peak power draw can be quite high. This may be the reason why causing the shutdown. The SATA port never designed to handle the GPU style power spike.
Last edited:
I've tried every possible solution using internal power, as previously mentioned, and it's a no-go. Of course it can be powered externally but that's not what I paid for. It seems I'll be forced to open a PayPal case just to get my money back and from what I've read he gets real nasty in that situation. I've confirmed a bone-stock Vega 56 has no problem running from both mini-6 pin on the motherboard.
Last edited:
You have not really answered the question. I asked if you had the card running fine as a mac in the macpro when you have external power , adequate external power, coming into the vega power ports ? If the answer is yes then none of the methods of powering it from the mac pro EXCEPT the pixlas mod will be adequate (assuming its an actual vega 64) , but the pixlas mod should be fine....
Sorry I missed that apparently. I does work fine when powered externally but that's not something I'm interested in doing nor am I capable of doing the Pixlas mod. To be clear this is a Vega 56 which should run just fine on internal power. The small performance gain offered by running the Vega 64 bios is completely negated by the fact it doesn't work in an unmodified cMP.
Every possible solution, including
1) dual mini 6pin to 8pin
2) 4x SATA to 8pin
And this config still trigger the shutdown protection?
easy way to tell a Vega 56 and 64 apart, even if both are reporting as Vega 64's
is fire up geekbench or some open CL application and see how many compute units are there
a Vega 56 will ALWAYS report 56 CUs regardless of ROM
K Funk
EDIT : Have you PM'd other VEGA 56 owners as to how they internally power their cards ?
I have often been 100% certain that I was right ! Correct ! only to find that I was wrong.
It may be that you did not do the EVGa PowerLink setup correctly.
I currently power my MSI Armor 580 8gb using the EVGa PowerLink which is not directly connected to the GPU. It sits on top of the PCI area Fan.
Please take a look at post#1
https://forums.macrumors.com/threads/evga-powerlink-with-amd-gpus.2166917/#post-27038019
In particular .. . this pic is important
the above photo shows how I setup the PowerLink for a flashed HD 7970
EDIT : IMPORTANT : Note that the 2 x sata to 6 pin go to the PowerLINK
Please tell us in detail how you did your EVGa PowerLink setup
======================================================
May I strongly suggest that you go here and make a Macrumors SIGNATURE including everything relevant to your cMP. Having a SIGNATURE will help us to help you - it will appear in all of your future posts.
As an example please take a look at my SIGNATURE below.
I currently power my MSI Armor 580 8gb using the EVGa PowerLink which is not directly connected to the GPU. It sits on top of the PCI area Fan.
I'm not using a Vega 56 but just to be clear re PowerLink setup here is my 7970 setup
It is very easy to get something wrong.
If, as you have stated, your Vega 56 works when powered externally it seems obvious that you have made a mistake in your internal cabling setup
Please tell us IN DETAIL how you did your EVGa PowerLink setup.
No one is condemning you - we want to help and if we are successful that solution will be very useful for other Vega 56 owners.
Last edited:
I can't connect 4x SATA to a single 8-pin nor would I, that shouldn't be necessary for a Vega 56. Perhaps I'm being unclear, this card is a Vega 56 using the Vega 64 bios and it that's why it shuts the machine down.
I've verified it's a Vega 56 with GPU-Z in a windows machine, the clock speed changes but not the stream processors. This card has 3582 which makes it a Vega 56 whereas the Vega 64 has 4096 stream processors.