m9750 with 9700m GT: Color Banding everywhere

Hello Alienware Friends

A few weeks ago my 8700m GT died and i could not find a similar card for replacement.
I thought i had found, but as it arrived it was a MXM HE/IV card that my m9750 simply dont liked - means it powered up but nothing else happened. Nothing on the Screen and no Hardrive activity.

Then i bought this 9700m GT (MXM III) and it works. I have that MXM Structure Error when i power my Alienware on, but i shrinked the 30 second beeping Message to 1 second. So thats OK for me.

What is not OK is that banding in nearly every Gradient. Even at the Vista Logon Screen i can see it. I work with graphics on my Alienware so this is a nogo.
Tried different drivers etc. Even when i boot off the Vista DVD the Setup Screen has banding in the gradients. Really drives my crazy.

Anyone here has any idea what i could try?

Thanks in advance,
Bot

 

OK, nothing yet.
I would be happy to get some ideas on this. Lets make this Part1.

Here is Part2:

As i already wrote i also have a 8700m GT here that is (even though i ordered MXMIII) HE Version.
When i put in in my m9750 and start it i can see the Display gets active but stays black. LEDs are on but nothing else happens. No beep, no Hardrive activity.
Any ideas to get this one to work?

Best regards
Bot