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MP 1,1-5,1 Radeon HD 7970 dropout

D

docone_DK

macrumors newbie
Original poster
Jul 24, 2018
11
3
Hi
I have just got a used AMD Radeon HD 7970 GPU. I have installed it in my 4.1 - 5.1 2009 cMP running Mojave.

But it has some dropouts where my screen goes black in 1-2 sec and the turns on again.

The GPU is not flashed so no boot screen and the power is 6 pin to 6 pin and 6 pin to 8 pin cable. My monitor, Eizo EV 3237 (32" 4K) is connected with a 5 meter mini DP to a DP an the resolution is set to 3840 x 2160 60 hz

The problem is almost the same if I set it to 30 Hz.

Have I got a faulty card og do it need more power or what?
 
Last edited:
Which maker for your HD 7970 ? EDIT : Sapphire ? Gigabyte ? MSI ? etc.

Are all of your internal SATA bays being used ? ( 4 in the PCI slot are and 2 in the DVD drive/PSU area) ?

Currently I use an MSI Armor RX 580 8gb but I flashed a Sapphire Dual-X 7970 for the rare occasion if I need to use Windows.

I have NO drives at all connected to my internal SATA bays ( 1 ~ 4 ).

When using the Sapphire 7970 it is powered like this ..

a. 2 X Mini 6 pin to 1 x 8 pin
+
b. 2 x SATA to 1 x 6pin ( NOT 2x SATA to 8 pin ! )

Both of the above cables go to an EVGa PowerLink's "Power Inputs "
forums.macrumors.com

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 forums.macrumors.com

From the PowerLink i use ( EDIT ) 1 x 8 pin male to female + 1 x 8 pin to 1 x 6 pin to the 7970.

EVGA Powerlink With Sapphire Dual-X HD 7970 in 2009 Mac Pro.jpg


Note 1 : I had to cut away a small piece of the Sapphire's fan shroud to fit the EVGa Powerlink
to the 7970.

Note 2 : To use the 2x SATA to 1 x 6 pin cable you can move two HDDs / SSDs to the DVD drives cage
there are even 4 spare, standard HDD drive screws attached to the DVD drive cage.
Note 2.1 : This assumes that you will now be without an internal DVD drive - I use an external ASUS
USB powered DVD drive, works faster than my original drive.

Note 3. The EVGa PowerLink comes with a spare 6 pin power input socket which can be used to replace
the factory installed 8 pin power input socket.
The reason that I replaced the standard 8 pin input power socket is that if one uses a 2 x SATA to 1 x 8 pin you run the risk of drawing too much power from the two cMP SATA ports for the 7970's 6 pin socket.

Note 4 : You don't have to use an EVGa powerLink but I endorse it as if will 'smooth out' power surges.
 
Last edited:
Thanks for your reply I will add more power.This week I moved the computer closer to the screen and therefor also changed to a shorter DP cable and then it all worked.
Could it be that the combination of the 5 meter cabled not enough power is the problem?
 
No matter what, your 7970 should still be powered correctly.

Which brand is your 7970 ? Sapphire ? Gigabyte ? MSI ? etc.
 
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