Apologies for the sloven reply Bruce42, year end accounts for HMRC took priority yesterday I`m afraid
We can only work with the info that we have so please bear with me;
The following was asked;
Is there an add on video card or only the MBs integrated video port/s.
How many sticks of RAM do you have.
To which you have replied;
The XPS8930 is just as it was purchased with no add ons,
and from your OP;
my new Dell XPS 8900
Your said model ships with various specs, example here
You mention in your reply #4 " I have removed the battery and discharged with the power button "
You appear to be comfortable with working inside of the computer so can I ask if you would be so good as to check for any add on video card and how many sticks of RAM there are.
Can you also let us know if when you try and power up the computer: The hard drive activity LED blinks.
Disconnect the computer from all sources of power, pull the MBs CMOS battery, leave out over night, reinsert/reassemble and test.
Remove and reseat the RAM, if you have more than one stick of RAM, try one stick of RAM at a time.
Will leave it at that for now and we will wait on your next update,