HD 6870 not being recognized when plugged in

Hello, I built my computer and got an ATI Radeon HD 6870 with it. After having some problems, I took out the card. I want to put it back in now, but when I put it in the screen stays black.

My specs:
AMD Phenom II X6 1055T Processor 2.80 GHz
M4A88TD-V EVO-3 Motherboard
4 GB DDR-3 mushkin
ATI HD Radeon 6870
Windows 7 Professional (x64)

I've been using my onboard graphics card, and when I put the card in and plug in the monitor it does not work. I went into BIOS and disabled onboard, but it still did not work. I manually reset BIOS to get onboard working again. I know the card isnt bad, because it worked before. I'm not sure if its important so I dont want to enable it, but is Plug and Play supposed to be set to ON? because it is OFF. Also, the BIOS graphics load order is
[GFX0-GPP-IGFX-PCI] and right now internal graphics mode is set to [UMA+SIDEPORT]