No display after GFX card change

[Telecaster]

So my shiny new card arrived this morning, I uninstalled the old card and it's drivers, plugged in the new one but I get no output at all.

PC starts up, all fans are working and all seems ok, but I don't get anything. Any ideas?

Old card is a 6850, new card is this one

http://www.overclockers.co.uk/showproduct.php?prodid=GX-013-VX&groupid=701&catid=56

 

[Telecaster]

This goes from bad to worse. I phoned OC for some technical advice just to see if I'd done anything wrong and the only thing he could suggest was updating the BIOS.

So I've done this via Qflash and now Windows wont start, it boots up to the Windows Error Recovery screen with 'Launch Startup Repair' and 'Start Windows Normally' options, neither of which work, it says it can't repair it.

So now I'm in no mans land with no idea how to sort it.

 

[Telecaster]

PC spec (from the top of my head)

550w OCZ PS
Gigabyte GA-Z77-D3H mobo
Core i3
16gb RAM (can't remember make without looking)
64GB SSD for OS and games
2TB HDD for storage
GFX was a HD6850
Monitor is a recent Dell 24" LED 1900x1200 connected via DVI
W7 64bit Ultimate

It all ran sweet, I was just looking for GFX upgrade and it's all gone a bit pear shaped.

I'm wondering if the easiest option is a reinstall of windows? I can't get in to do anything, it gives me the system restore options, recover from image etc etc.. but nothing works.

I have the error report after it has tried to repair if that is any help.

Edit: FWIW the BIOS update went fine and it boots up fine up until trying to load windows.