11,1 Dual boot High Sierra and indows 11

[Procrastinus]

After resurrecting a 27" iMac 11,1 by baking the card, I used the same basic technique that I used here to install High Sierra and Windows 11. If the Windows installation halts at the later stages, just shut down, reboot to the installation USB and select Repair. Cirrus sound driver can be found in BootCamp 4.0.4033 and the Bluetooth driver at here. All other drivers seem to install themselves.
To solve the overheating problems that plague this model I was inspired by this.
So I drilled two 8mm holes at either end of the top narrow ventilation slot and used an angle grinder to connect the holes, a file finished off any rough edges and silver auto paint matched the existing finish. I should mention, remove glass and screen first and tape up the inside top grill to keep swarf out of the machine. Sounds rough, but with care one can achieve an excellent finish,
Now two great systems with a lovely broad screen and runs cool too with MacFan!

 

[newbutter]

Sounds like you've done a great job resurrecting that iMac and getting it to dual boot High Sierra and Windows 11. The workaround for the overheating issue is pretty ingenious too! Cheers!