Two different GPUs, three monitors (DVI, DVI and HDMI)

[fffffffff]

I have Win 7.

Main GPU is 280X, second one is HD7870. I have two monitors connected to the 280X, both through DVI. I want to use the second GPU (HD7870) to duplicate my main monitor and send the signal through HDMI, so I have my third monitor connected through HD7870 with a HDMI cable, but I get no signal from it because I think Windows tries to send the signal from the HD7870 through VGA instead of HDMI.

http://i.stack.imgur.com/ybUNY.png

 

[fffffffff]

I just got it working, the problem now is that I can only use the monitor connected to the HD7870 as extended. I cannot duplicate it with my 1st monitor.