AVI works, DVI no input to monitor. Troubleshooting?

I have four monitors supplied by two identical Nvidia Geforce 210 graphics cards. I don't always have all four switched on, it depends what software I'm running as to whether I need them all or not. Recently one of my monitors, a 1920x1200 Iiyama 2607 has started giving me problems as it wouldn't always come on when I turned it on, but when that happened, if I logged out and back in (or sometimes if I rebooted) it would come on. I noticed that my graphics card started to describe it as a Generic pnp display rather than name it as a Iiyama 2607. All my other monitors are identified/correctly named by the graphics cards, and I think when I first installed it, it also was identified as an Iiyama. All four monitors have been connected digitally (two by DVI, two by HDMI into the graphics card with an HDMI->DVI adaptor into the monitor).

Just recently I've not been able to get any DVI input recognised by my Iiyama. I've tried both graphics cards, both DVI and HDMI sockets. I changed the DVI cable (though both my spare DVI cables are identical and pretty cheap so I can't exclude a problem there). I tried plugging the Iiyama into a different computer DVI socket, still no DVI input. I've done monitor factory resets, no DVI input still.

However, VGA works fine (other than being a high resolution the screen is a bit blurry so I'd like to get a digital signal back if possible).

Is there anything anyone can suggest that I haven't yet tried, to test for the problem or to get a DVI working again on the Iiyama? I read somewhere about EDID getting corrupted when graphics cards say "generic pnp", if that's happened to my Iiyama then can I mend it from my computer without goosing the monitor and stopping the VGA from working too, since that's my last resort if DVI is not working? How would I change the EDID on the monitor if it refuses to recognise any DVI signal?

No suggestions?

Maybe the monitor's DVI port is faulty or damaged.
Update your graphics card driver.

Thanks - all Windows and graphics card updates are fully up to date so don't think it could be that.

Can't see how the DVI port could have been damaged since it hasn't been touched nor has the monitor been moved since I set it up three years ago (until I changed cables recently to see if the cable was at fault - and found that the cable change made no difference to the monitor). Too bad if the monitor has a hardware fault.

You can use VGA, it should work good.