If your cards lights are cycling every 2-3 seconds that seems to me like either the bus is resetting the card, or the card itself is resetting. You might try manually assigning different IRQ's to the card and insuring that the PCI slot you are using is not shared by anything else like a COM IO chip or Sound chip or the like. Most desktop grade boards share 3/4 of their PCI slots with on board hardware. Dual/Quad nic's DO NOT LIKE this at all.
If you notice, most DUAL/QUAD nic's will not run on PCI splitters installed on single PCI 1U servers. They have warnings in the manual about this. So if the PCI slot you have the card in is split with anything else, this may be leading to the behavior you're experiencing.
I would turn off everything in the bios that's not completely necessary including com ports, parallel etc, freeing up IRQ's. Then make sure your card gets IRQ's that are not used by anything else. Also avoid IRQ 11/12 if you can. 12 being the PS2 port. Older boards favored IRQ 10 for the video card. IRQ3,4,5,7.9 should be free if you turn everything off.