K4100M boot loop

[amily2011]

I bought it and installed it on iMac 2011 but it doesn't work. Symptoms boot loop I can't boot to flash. And then turn off
Two LED on

 

[Nguyen Duc Hieu]

The card has been flashed with compatible ROM?

 

[amily2011]

The card has been flashed with compatible ROM?

I haven't flashed yet When I finished the setup, got ready to boot usb, my friend flashed, but my screen is not showing at all What should i do

 

[Nguyen Duc Hieu]

I haven't flashed yet When I finished the setup, got ready to boot usb, my friend flashed, but my screen is not showing at all What should i do

1) Flash it with compatible ROM. You need another machine to remote control the iMac with K4100m installed, and boot from a special made USB to Linux. Go to the first post on the famous thread 2011 iMac GPU upgrade to find necessary info and files to build the Linux USB.

2) Check if the iMac is still functioning with a stock GPU.

3) if both 1) & 2) are OK, your should get the screen showing boot screen when pressing Option on boot.