XFX HD 7870 DD No signal

[Junpaku]

The GPU I had installed on my PC is GT 210. I uninstall the nvidia drivers and rebooted it. Then, I turned off the computer, installed the 7870 onto the mobo and connected one 6 pin to it (my current PSU has only one 6 pin). When I start up I get no signal on monitor. Next I remove the 7870 and start up with onboard so I can get into BIOS and disable onboard graphics and enable PCI. Then I reinstall the 7870 and connect the 6 pin and then start it up, still no signal. I reinstall Win 7, repeated steps above and still wont work.

Notes: I am using a DVI to VGA Adapter since my monitor only has VGA. The fans on the 7870 do spin. When I disable onboard and enable PCI while using GT 210 I get signal.

Specs:
CPU: i3-3220 3.30 GHz
Mobo: GAB75M
PSU: CM 500 watts
1st GPU: GT 210

Any help is appreciated.

 

[Junpaku]

Self bump.

 

[djosbun]

My first guess is that you might have a bad DVA/VGA adapter. Any way you can test with a different monitor?

 

[Junpaku]

Thanks for the reply djosbun. I have tried using the DVI/VGA adapter on my GT 210 and it works. I have also tried using a different monitor with the 7870, still doesn't work.
Windows seems to start up (because I can hear logon sound), but it won't detect the 7870.
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Edit: On BIOS I had "Init Display First" and "Internal Graphics" on "Auto", while using 7870 with VGA/DVI adapter and VGA cable, I still get no signal. When I switch the VGA cable to the onboard (While windows is booting w/o signal) I get onboard display. Its as if the card isn't being detected at all.

 

[Junpaku]

I fixed it. Bought a molex to 6 pin. Thanks for the help.