Resolved RX 480 shutting down flashed 4,1, need different power cable?

tpivette89

macrumors 6502
Original poster
Jan 1, 2018
498
257
Middletown, DE
I have a 4,1 that I flashed to a 5,1 and gave to my son for basic web browsing and light gaming. He exclusively plays Roblox on the machine. I installed a Radeon RX 480 (8gb) which uses a single 6-pin connector. However, randomly, the machine will shut down after a few minutes to about a day from him playing this game. I'm thinking it is the GPU that is causing this, as I installed the stock Radeon HD 4870 and no shutdown has occurred since.

Is it possible that the single mini 6-pin to 6-pin connector isn't supplying the card with enough juice? Is there a dual mini 6-pin to single 6-pin cable that I can purchase to funnel all available power to the single 6-pin port on the RX 480? I did some light Google searching, but came up empty handed.

Thoughts?
 

tsialex

macrumors 604
Jun 13, 2016
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Brazil
Is it possible that the single mini 6-pin to 6-pin connector isn't supplying the card with enough juice?
Yes, when using just one PCIe power cable, RX-480 and RX-580 uses more power from the PCIe slot causing shutdowns.

Is there a dual mini 6-pin to single 6-pin cable that I can purchase to funnel all available power to the single 6-pin port on the RX 480?
Yes, sometime ago was a relatively common cable, but now seems no one is making it anymore. Maybe someone will know where to buy it today.
 

h9826790

macrumors G5
Apr 3, 2014
14,245
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Hong Kong
For RX480, I don't think it will draw more than 120W from the 6pin (which trigger the shutdown protection).

However, it may draw more than 75W from the PCIe slot. This is a known issue for the reference RX480. And there is no fix for cMP in macOS.

AMD fixed this issue in Windows by using driver update. And there is no such update available in macOS.
 

tsialex

macrumors 604
Jun 13, 2016
7,867
8,488
Brazil
For RX480, I don't think it will draw more than 120W from the 6pin (which trigger the shutdown protection).

However, it may draw more than 75W from the PCIe slot. This is a known issue for the reference RX480. And there is no fix for cMP in macOS.

AMD fixed this issue in Windows by using driver update. And there is no such update available in macOS.
Maybe flashing it with some low power RX 580 firmware, like the Dell RX 580 card that still uses Polaris 10, can make this work better.
 

h9826790

macrumors G5
Apr 3, 2014
14,245
6,849
Hong Kong
Maybe flashing it with some low power RX 580 firmware, like the Dell RX 580 card that still uses Polaris 10, can make this work better.
May work. But unless I have both ROM on hand and compare them, I still can't quite sure that OEM RX580 has an updated ROM which already fixed this issue.
 

startergo

macrumors 68020
Sep 20, 2018
2,307
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If I'm not wrong @startergo has one of the Dell RX 580 with just one PCIe power connector.
I had some shutdowns in Windows during furmark test under certain condition. I was physically measuring the current with a clamp meter and fluke meter. When I connected the 2 6 mini connectors and repeated the test there were no more shutdowns. Apparently it was spiking more than 120W
 

krakman

macrumors regular
Dec 3, 2009
236
236
I know few cMP owners using that OEM RX580. But I am not sure if they use this GPU for playing games.

Video editing's demand seems quite a bit lower than gaming.
I have 3 cMP with reference rx480 connected via single mini 6 pin to 6 pin, never had a shutdown but our use is FCPX and photography, not games.

I would follow the suggestions about getting a dual mini 6 pin to 6pin cable.

You might also look into using a EVGA Powerlink adaptor to smooth out the power draw. search this forum for details....
 

tpivette89

macrumors 6502
Original poster
Jan 1, 2018
498
257
Middletown, DE
Just realized I never updated this thread with results... bought the cable in the link above and have had no random shutdowns since. Apparently, even though the RX480 has only a single 6-pin connector, it needs to be fed by both GPU power outlets on the logic board to run smoothly.

Of course, my use was for online gaming (my kids play with a second 4,1 that I have setup... this was the machine that was shutting down). For other use cases, it may not be necessary.
 
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