Mid 2011 iMac (27”) flickering glitchy unusable screen

Hi all,

My trusty old iMac started flickering a few weeks ago. Within a couple of minutes the screen showed lots of graphical artefacts and was unusable, though the Mac itself turns on and appears to run fine, even though it’s impossible to see what’s happening onscreen.

I suspect this is something to do with the graphics card (AMD Radeon 6970) maybe having packed in. A year or so ago I also replaced the HDD with an SSD and used a fan control app, so not sure if this could have developed into an issue after that time. Was well out of warranty then so wasn’t too concerned and it was well worth it.

Luckily I discovered I can do my work from my iPad Pro and connect to my work computer virtually, but I have two questions:

1) How would I start up my Mac to bypass the graphics card to use onboard graphics to see if I can confirm the GPU is the problem? Target disk mode or something?

2) Seeing as it looks like I’m actually ok working on my iPad Pro without my iMac, is it still recyclable for money with a broken graphics card or would it just be ‘recycled for free’ but not net any sort of money return?

Thanks in advance!