6 x GPU mining rig only installs drivers for 5

Question

I built the following rig:

• 5x SAPPHIRE TRI-X R9 280X 3GB GDDR5 OC (UEFI)
• 1x AeroCool Templarius Imperator 1150W 80 Plus Gold
• 1x HighPower Tech 1200w Gold Plus (HP-1200-G14C-GOLD)
• 1x Asrock H61 Pro BTC Mother board
• 1x W.D Caviar Green 500GB SATA III HDD
• 1x Kingston KHX1600C9D3B1/4G
• 6x Powered risers 1x 16x

I Installed Windows 8.1 and plugged one GPU. It automatically installed the Radeon HD 7990 driver. Then connected the second GPU and followed the same process with the other GPUs. Everything works fine for 5 GPUs. But for the sixth one, it won't install the driver.

I try to update the driver of the sixth one but it says that the last driver is already installed.

Regards,

Answer 1

(since I can't comment) I had this problem too about a month ago. Try using AMD Catalyst to install the drivers.

Answer 2

The real answer: Sell all of your graphics cards immediately and buy coins with the proceeds. you will never pay for the cards with all of their future mining combined at this point. If you believe in litecoin or altcoins, buy them. If your goal was to mine and exchange for bitcoins, buy bitcoins. The current estimator has 1 MH/s as being worth $127. Even if that holds for 3 months (doubtful) and you have free power (doubtful) you will have more than $380 in depreciation as people begin to sell their cards. When asics come out, you're done. Gross revenue will go to $10/month easily.