GPU Post Tool Not showing 2 cards

[coconuts4eva]

I just bought an Asus X99 E-WS.

 

I have four GTX 780s that I know work fine.

 

I put them on the motherboard (slots 1,3,5,7). The Asus UEFI GPU Post tool shows my GPUs in slot 1 & 3. The other two do not appear. I also tried some other graphics cards in slots 5,6,7 and they don't show up either. 

 

It boots fine, but the two cards aren't showing up. I've updated to the latest BIOS. Am I missing some BIOS setting?

[Gonio]

Is that the proper SLI slot? Check manual for what slot you need to use. Also should check if the mobo has extra power connection for the PCIe slots.

[coconuts4eva]

23 minutes ago, Gonio said:

Is that the proper SLI slot? Check manual for what slot you need to use. Also should check if the mobo has extra power connection for the PCIe slots.

Thanks. Not using SLI. I'm using the slots recommended for four cards. I've got the extra pcie power connector connected too. I should also say that all the cards are lighting up. They just don't show up in the device manager or BIOS.

[Gonio]

You have all 4 installed? Anyway if you don't use SLI, maybe you still need the bridges? You tried that?