Fenix793, don't chuck the GFD! I had the exact same problem, I use the same Northwind 3.0 on an Athlon 650. The first time I put it on, I had the multiplier set to the same setting as my 'default' CPU, in my case 6.5x, with the voltage @ 1.75. It wouldn't even post. When I removed the GFD, booted normally.
Then I remember going into the BIOS (my mobo is the Abit KA7) and setting the FSB and voltage all back to default, i.e. FSB=100 and V=1.6. I had previously been overclocking via the FSB settings.
I shut down, reattached the GFD (I think I even moved the dipswitches to give me a 7.5 multiplier), and booted up. I was pleased to see it post, Athlon @ 750 MHz. And currently I'm running at 850, 1.85V.
OK hope there's something there that is helpful to you.