From the service menu and screen characteristics (orange tinge at extreme angle), it seems to be an S-IPS panel. And yes.. it has some colour banding on some gradients. Bought it this year from Dell with 4 years of warranty.. I wonder how are they going to do with it if it go kaput anytime soon.. (touchwood)
Shouldn't be an issue with the display connected should it?
What does your serial end in--P = PVA, S = S-IPS.
And no it's not the display; I was just curious because I have the same monitor with S-IPS.