Hello friend, as i wrote in title i have rx560 which i bought as damaged with knife (little scratch on pci lines). I Connected everything and video show up, but while i was running furmark i had black screen, tried to reboot but mobo beeps as card is not connected. I turn off and on psu and GPU worked again, but the same issue, in furmark or etc i get black screen. After that i though it can be windows 7 problems so i installed fresh windows 10 and while installing it the fans of gpu ramped up to 100% and stuck that all the time. MSI afterburner and other apps cannot change fan speed (138%speed lol) but the gpu test after that was fine and no black screens (i'm not perfectly sure because test was about 10minutes cause of that angry loud of fans). I decided to change fans from other fans and control of fans started working again, i can change speed of fans but i have the same issue that earlier with black screens :|

What it could be guys?

I tried reflow too all the card - nothing happend, Tried lower clocks of memory and gpu to minimum in afterburner - nothing happend.

Thank you guys!

I forgot, black screens in furmark are not instant, it works about 2 minutes before black screens. Gpu temp before is about 55degress celcius. After black screen when I left it for a while it cools down so gpu is not working when black screen.

I tried on other motherboard, and got the same black screens in liad, what cause that problems guys? I don't have any idea :(

1) GPU clock + powerlimit on MIN.
2) PWMs on GPU fases?

When clock, memory and power set to -75%TDP is working fine, when i set clocks to normal and TDP-75% still fine, but when i set TDP to -65% black screen. To measure PWM on mosfets should i disconnect every phase and measure output of the mosfets or only should i connect osciloscope to phase? I didnt do that earlier.

Connecting osciloscope to phase is the way.

All measurements should be taken at the max load that didn't cause black screen (-75% I think). Don't measure on light desktop-only load - for such case it can turn in power-saving mode that looks different.
There are two ways to measure:
1. Standard phase measurement: oscilloscope ground to the card ground, probe to phase before coil; check that all phases oscillating pictures are similar.

2. Extended/non-standard phase measurement (do with caution and thinking on your own risk! be sure that nothing extra will touch oscilloscope ground): oscilloscope ground to the card 12V, probe to phase before coil; you should check that while high gate is open - all phases stabilizes near 12V in similar way.
See my example pictures with different phase behaviour (one picture is for a non-working-fine phase) at viewtopic.php?p=806536#p806536

I performed the measurement 2 on some more cards - and found that nearly all of them has picture similar to "bad" on the link above on all phases, and this is fine.
So it's important to see "is there a difference between phases", not "does all phases similar to good or similar to bad".

Ok i measured and all phases looking good as in your photo (i attached that) and i discovered something, even on everything (clock gpu, mem, power) set to minimum in furmark i got still black screens but msi kombustor seems to work.
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All phases seems to be the same as others, i attach all phases.
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It was tested your second method

Is GPU dead?

Mem - 100%, GPU - 100%, PL - 75..80%. Furmark. Results?

Marking MOSFETs (up + down) ?

On mem 100% (normal clocks) gpu 100% (normal clocks) and pl +75% (175%) in furmark black screen after 15sec.

Mosfets are aon 6508 and aon 6414a
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If u mean that clock and power :)
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Oh i read bad, with power set to 75% - 30 sec in furmark and black screen.
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Strange for me is that I need to wait a while (3-5minutes) with psu power off to start card again after black screen, look like some capacitor or something like that?

But if mem=75%, GPU=100%, PL=75% all is Ok?

...or tempetarute?

I mounted again heatsink and with that setting as you write black screen in furmark was after 90 seconds. Temperature of gpu before black screen was about 55/60c degree.

not GPU, but MOSFETs

So how to check mosfet temperatures?

Thermal imager, thermocouple, pyrometer... finger.
For your MOSFETs - u better change them on analogs, but with Id more than 32A.