Greetings Vogons!

I'm in the process of building a Vista machine and currently having a weird issue, but first here are the specs:

Asus P5E3 Premium/WiFi-AP (latest BIOS)
Intel QX9650 @ stock
2x1GB Corsair 1333MHZ DDR3
2 x Asus 4870 1GB Dark Knight
500GB Sata HDD
Thermaltake GT 850W (brand new)

One of the Asus 4870 GPU is not being detected at all. I was getting the one long, then three short beeps. The other Asus 4870 works just fine.

I tried the non-working 4870 to my other computer and it posted just fine. So I know that the GPU is working.

Here's what's weird:

I have two more 4870 cards. A PowerColor 1GB and Diamond 512MB. Both these cards work on the P5E3. Tried them individually and in crossfire.

It's just one of the Asus 4870 1GB that doesn't work with the P5E3.

I was so desperate, I took the P5E3 out of the case and tried to use the black PCI-E slot (limited to 4x speed I believe), and it posted! But no matter what I try, it still doesn't post on either of the two blue PCI-E@16x slots.

If the GPU is bad, it won't work with my other computer. It also posted when plugged in to the black PCI-E slot.

If the motherboard is bad, all four 4870s won't work. Three 4870s work just fine using both blue PCI-E@16x slots. It was just this one Asus 4870 1GB card.

Is there something that I can do to make this work?

Thanks!