2nd video card (mach64) not working

[BennyP]

I use a Voodoo5 agp for my main display, but i just got an ati mach 64 pci, so i plugged it in and got out an old monitor (compaq presario v410)
I can't seem to get it to work though! the monitor just shows a blinking black and white grid pattern all the time (i think this might actually be a monitor problem!)

anyways, i enabled the atyfb module in my 2.6 kernel, but i still can't see anything on my 2nd monitor

How can i enable dual head with this video card??
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Could it be?