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siox23

macrumors newbie
Original poster
Oct 26, 2019
22
5
Hi,

I know this config with this issues have been discussed before, however, I went through all these threads & posts but I still have problems with my machine.

maybe I its good to know that after I bought the machine I gave all boards complete clean with isopropanol (8 hours of work), cleaned the psu (disassembled it), sticked 2x3,06 ghz processors in it, repasted and fixed the northbridge mount. everything went flawless, also firmware upgrades and install of Mojave without any problems.

here we go:

rx580 (sapphire pulse, 8gb) powered by dual mini 6pin top 8pin adapter. file vault deactivated. this setup worked without problems for 5 months.
suddenly the machine rebooted during easy tasks like browsing. sometimes also distorted screen.

solution: used a external ATX psu to power the gpu - worked.

conclusion: to less power from motherboard.

possible fix: pixlas mod.

after pixlas mod: machine not booting. no chime. black screen. fans of the GPU spinning, measured 8pin pcie cable - everything like it should be. mod was done right.

next: smc and pram reset.

after pram reset: got the boot chime back. but machine stays in a boot loop. diagnose button shows that psu is okay and that during the loop the EFI loads.

next: booting without gpu: machine boots. no loop. cannot verify if it boots until the boot screen - don't have the required network hardware here to access via remote access.

conclusion: faulty GPU or PSU problem

test1: rx580 in sonnet breakaway box. works with mbp 2017. GPU seems fine.

test2: powering the rx580 with external ATX psu (you remember this worked before) - again boot loop / black screen.

next: minimal configuration procedure. everything okay until I stick the GPU in the machine = boot loop.



....

used PSU's costs 150€ in my area. should I give it a try?

any help appreciated.
 
Hi,

I know this config with this issues have been discussed before, however, I went through all these threads & posts but I still have problems with my machine.

maybe I its good to know that after I bought the machine I gave all boards complete clean with isopropanol (8 hours of work), cleaned the psu (disassembled it), sticked 2x3,06 ghz processors in it, repasted and fixed the northbridge mount. everything went flawless, also firmware upgrades and install of Mojave without any problems.

here we go:

rx580 (sapphire pulse, 8gb) powered by dual mini 6pin top 8pin adapter. file vault deactivated. this setup worked without problems for 5 months.
suddenly the machine rebooted during easy tasks like browsing. sometimes also distorted screen.

solution: used a external ATX psu to power the gpu - worked.

conclusion: to less power from motherboard.

possible fix: pixlas mod.

after pixlas mod: machine not booting. no chime. black screen. fans of the GPU spinning, measured 8pin pcie cable - everything like it should be. mod was done right.

next: smc and pram reset.

after pram reset: got the boot chime back. but machine stays in a boot loop. diagnose button shows that psu is okay and that during the loop the EFI loads.

next: booting without gpu: machine boots. no loop. cannot verify if it boots until the boot screen - don't have the required network hardware here to access via remote access.

conclusion: faulty GPU or PSU problem

test1: rx580 in sonnet breakaway box. works with mbp 2017. GPU seems fine.

test2: powering the rx580 with external ATX psu (you remember this worked before) - again boot loop / black screen.

next: minimal configuration procedure. everything okay until I stick the GPU in the machine = boot loop.



....

used PSU's costs 150€ in my area. should I give it a try?

any help appreciated.
Your PSU could be dying. Did you tested with an Apple GPU, preferably a GT120?
 
i have a second machine in my studio with a gtx680 2gb, apple firmware (dos dudes rom).

but what is the conclusion if the computer works with the 680? it should work with rx580 and the card is obviously not defective if it works with the sonnet breakaway box.

hmmm.
 
About that pixlas mod:

8 pin gpu should work with a dual mini 6 pin - to 8 pin cable.

8 pin maxes out at 150 watts per definition.

One single mini 6 pin provides 75 Watts per specs. And about 110 Watts in reality.
 
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