Make sure your graphics card is seated correctly and in the right type slot (eg, make sure its not an agp in a PCI slot), your motherboard can accept it, your power supply is powerfull enough, check its not overheating, do you have the 6 pin power cable plugge din properly (of needed) or the card might be dead.
Also try disabling on board VGA in your BIOS if you have it.
Try onboard, and if possible, another video card. Start out with only the essentials. Take out the HDD, opticals, sound card, and anything else. Try starting with those.
No, the motherboard has it's own "integrated" (on the board itself) video card. It stinks, but we can troubleshoot with it right now. Take out the 8600 and plug in the onboard. It should be blue and right under your mouse and keyboard slots. If you do NOT see it, try your other video card. (only some motherbords have integrated video)
Hmm
What was your prior card?
If it was AMD, you could have a driver conflict.
Hm... Did you buy the card new?
Do the fans spin?
DDR2 Comes in 400? It must be, because it wouldn't fit in the 240pin slot if it was DDR1... Weird.
Wow, never seen a mobo like that (I saw it once but didn't think it was MOST MOBOS THESE DAYS) are you sure about that?