Use a iMac Late 2009 with GPU Issue as external monitor

[Phoenix Fire]

Hi to all,
I have a friend that has a late 2009 27" iMac. He says that his iMac has strange lines during the normal execution, so he take it to a repair shop that ask 180€ to partially fix it. I say partially because they explain that the fix should solve the screen problem but the gpu can't sustain high load. This he choose to buy a new one and ask me if I am interested. Long story short, I think to use it as an external monitor (it is a 2k 27" for free), but I don't know if the gpu problem affect also the the use as Target Display.

 

[USB3foriMac]

They likely "bake" it. Read up on "bake imac GPU".
For replacement, see GPU thread here.
GPU problem will of course also affect TDM. If you want to go down the route of display only, you can buy a LVDS controller card which will then have a HDMI input. Search for such card on LAiexpress with your display model number to find the right controller card. Frankly, baking yourself is easier than this mod.

 

[Nguyen Duc Hieu]

Hi to all,
I have a friend that has a late 2009 27" iMac. He says that his iMac has strange lines during the normal execution, so he take it to a repair shop that ask 180€ to partially fix it. I say partially because they explain that the fix should solve the screen problem but the gpu can't sustain high load. This he choose to buy a new one and ask me if I am interested. Long story short, I think to use it as an external monitor (it is a 2k 27" for free), but I don't know if the gpu problem affect also the the use as Target Display.

Please tell me: what prevents you from experiment it for free?
Does you friend live very far from you?
I would just drive to his place, bring along with me a PC with DisplayPort video out, one DisplayPort to MiniDisplayport cable, and test it right there, before deciding.

I think iMac operated in Target Display Mode only re-route video signal from the external miniDisplayport (on the back of the machine) to the eDP port (on the logicboard) connected to the LCD screen, but that's perhaps my pre-mature assumption anyway.
An LCD control board for iMAC A1312 LCD cost around $70 on Aliexpress, but you need some skills to DIY your 27" 2K monitor.
Another option is second hand K610m MXM card (~36$)

 

[Phoenix Fire]

Please tell me: what prevents you from experiment it for free?
Does you friend live very far from you?
I would just drive to his place, bring along with me a PC with DisplayPort video out, one DisplayPort to MiniDisplayport cable, and test it right there, before deciding.

I think iMac operated in Target Display Mode only re-route video signal from the external miniDisplayport (on the back of the machine) to the eDP port (on the logicboard) connected to the LCD screen, but that's perhaps my pre-mature assumption anyway.
An LCD control board for iMAC A1312 LCD cost around $70 on Aliexpress, but you need some skills to DIY your 27" 2K monitor.
Another option is second hand K610m MXM card (~36$)

My friends live far from my home, thus I don't want to take it and then don't use it. I prefer that my friend give it to some other in that case.
It is so cheap the graphic card? I can think of replace it and use the iMac for office and internet other than second screen when I need the power of the MacBook

I bought a usb-c minidp cable on amazon. I will try it

 

[Phoenix Fire]

They likely "bake" it. Read up on "bake imac GPU".
For replacement, see GPU thread here.
GPU problem will of course also affect TDM. If you want to go down the route of display only, you can buy a LVDS controller card which will then have a HDMI input. Search for such card on LAiexpress with your display model number to find the right controller card. Frankly, baking yourself is easier than this mod.

I do not know what they do, my friend is not an expert so he didn't ask many questions. I want to know if it is possible to use as target mode display mainly because (in my opinion) it in some way bypass the internal card, obtaining an old 2k 27" for free. Then, I will think on repair it if it is possible in some cheap way (e.g. replace the card)

 

[Nguyen Duc Hieu]

My friends live far from my home, thus I don't want to take it and then don't use it. I prefer that my friend give it to some other in that case.
It is so cheap the graphic card? I can think of replace it and use the iMac for office and internet other than second screen when I need the power of the MacBook

I bought a usb-c minidp cable on amazon. I will try it

OK, I've just install a AMD Radeon WX4150 to my iMac mid-2010. (flashed with GOP ROM)
The screen is totally black when I turn it on. No video signal from mac OS to the internal eDP port, thus I couldn't see anything.
But when I connect my HP 800G1 USDT to the iMac via Displayport to miniDisplayport cable, it just showed Windows.
Just some info for your confidence in using your iMac as monitor for another machine.

 

[Phoenix Fire]

OK, I've just install a AMD Radeon WX4150 to my iMac mid-2010. (flashed with GOP ROM)
The screen is totally black when I turn it on. No video signal from mac OS to the internal eDP port, thus I couldn't see anything.
But when I connect my HP 800G1 USDT to the iMac via Displayport to miniDisplayport cable, it just showed Windows.
Just some info for your confidence in using your iMac as monitor for another machine.

thanks for your answer. You make me hopeful