Radeon Diamond 6990 dose'nt load at boot but windows does?

[Xenland]

Hello chat I just got the radeon 6990 Made by diamond. At first I thought the card was not in the PCIe slot all the way so I pushed it in and heard the *click* so I thought i would deffinatly boot up. Obviously it dose'nt.

This is what happens when i try to boot,
Blank screen the whole time, no post, no BIOs.

Windows does infact boot up becuase i hear the gingle when it comes to the login screen.

I read in the instruction manual that I should disable the on board video when trying to install but this shouldnt be a problem yet scince im trying to get to linux and i cant with out seeing the boot screen or the bios.

I see there is some things on top that look like power conntections but it didnt look like it came with those types of cords. Any suggestions?

[Xenland]

I guess is all my awe of my supposed Dell XPS 8Gigabytes of ram, multi-core super computer, I forgot to check my power supply and its 420Watt....yeah no wonder my card wouldn't boot

[Atroxes]

Dell is notoriously known for only JUST providing enough PSU power in their setups.

Get a friend to build a machine for you next time, you'll thank him later

[Xenland]

Alright, so i upgraded the psu to a 1000watts and plugged in the 6990.
Windows will boot so But it only boots with the on board graphics card.
I try to switch to digital and it switchs back analog and i unplugged the analog and it will say no signal.
Windows at first reported Video controller so i installed the drivers, i rebooted.
It booted up to on board video card  again. Again it reports no signal unpkugging the analog cable it should switch to digital(i tested this with another computer with the same  monitor).
Windows at this time reports two 6990 displays in the video display options. Along with the onboard video card.the wierd thing is that i disabled the onboard video card and windows 7 reports that it is disabled although it still uses the onboard.

UPDATE: looks like the problem was my monitor, the Digital cable line was broken, i tried with a different monitor and it detected it is right away. This was after I uninstalled the onboard card instead of just setting to disable so it was probably a number of things