Will a motherboard that is compatible with the GT8800GT be compatible with the GTS450? Using XPS720 mobo?

Hi I just received my new GTS450 (EVGA) 1024mb



I installed the hardware (just put it in sideways and make sure it fits etc) + powercable

I uninstalled/reinstalled GT 8800 GT like that and it worked out, so I'm not sure why this isn't working.



When I plug in the cable to the computer it recognizes that something got plugged in because screen's power button changes color, but then it tells me NO SIGNAL DETECTED.



Now I tried this with my old video card and that has also stopped working (though I did kinda stop using it because its broken but it does at least load up to home screen for about 15 mins first (always) before it stops.



I've tried regular VGA - DVI with two different moniters but neither of them can get a signal (both monitors work with my laptop.



Any solutions?



P.S Power Supply is 950w, I'm using the power cables that I used for my GT 8800 GT they all look the same too (fan is spinning on new card though)



I installed it into blue slot





http://www.nvidia.com/object/product-gef…

uses PCI-E 2.0 16x

(1024mb)



http://www.nvidia.com/object/product_gef…

Uses PCI-E 2.0

(512mb)





If it might incompatible with my motherboard its the XPS720 one.



Sorry I'm new and very lost|||It should be compatible with your motherboard.



Can you reinsert the 8800 GT and get it to boot? If so, uninstall the old nvidia drivers before shutting back down. Video cards work fine at low resolution using the default VGA driver, but can't always handle outdated video drivers.



Do you see ANYTHING on your monitor when you reboot the PC? (Use the power switch if needed to force a reboot). If the card is installed correctly, you should at least see the POST or DELL Splash screen appear.



EDIT -

Two things come to mind. Let's try the easy one first.



If you're new to this, are you making certain that the PCI Express retaining tab is locking the bottom of the card into place? Make sure the 6-8 pin power cords are firmly seated in the card. A loose connection would explain the problem nicely, and be an easy fix. http://support.dell.com/support/edocs/sy…



Otherwise, I'm worried that something else was disloged or disturbed while the video card was being exchanged. The system isn't beeping at you during startup by any chance? That might happen if the video card is identified as being removed. Otherwise, check all the power connectors and make sure none of them were jarred loose.



If none of that works, it's time to take it to the shop.