I gave up and changed my VGA to GTX 1050 ti. Now everything works 100% ok.
Sad to say but 10.13.1 looks not so different from 10.13 on my GTX660 hack, either the UI appearance or the graphical glitches and artifacts
how is HD4000/4600 perform? I heard this issue doesn't exist who use intel HD graphic cards.
I was thinking anyway to buy a GTX 1080 Ti, to make of use my 4K TV... will a setup like this work as expected with High Sierra?
Thanks for reply!! Finally I decide to give up and order a PowerColor AXRX 580 RedDevil 8G video card. It was approved to be compatible with 10.13 and theoretically further updates. For the possible additional power consumption, I also order a 750W Corsair power supply to swap my present 500W one.Indeed, I completely removed my 660 card from the motherboard (I didn't have any luck when it was connected), added inject intel vga in clover and it worked. The Desktop was as I was used to, no surprises there. Everythin works smoothly.
I also had the nerve to check on a game, especially DOTA 2. The performance was a joke, but it was something.