Only 3 of 4 X290 detected

[bananabeast]

Hi guys,

we just recently built a system and have issues with the 4th card.

Hardware:
Motherboard: MSI Big Bang-XPower II (MS-7737)
CPU: Intel Core i7 @ 3.70GHz Ivy Bridge-E 22nm Technology
GPU: 4x 4096MB ATI AMD Radeon R9 200 Series (Sapphire/PCPartner)

According to our main board we have 40 data lanes for the GPUs,
There are 7 PCI express sockets:
4 times 16x, 3 times 8x

Also according to the mother board specification we can have 4 GPUs installed in the configuration:
1, 3, 5, 7
which would lead to:
16x, 8x, 8x, 8x

Unfortunately, there are only 3 GPUs shown in our Hardware monitor, GPU-Z, Speccy, Catalyst.
oclHashcat only shows 3 GPUs, but works fine with those 3.

I have enabled all 4 PCIe on the motherboard.

The bios does not allow me to configure any more options for the PCIe, in fact, they are not even shown.

All drivers for the motherboard, chipset are installed.

Could anyone think of a solution? Any help is kindly appreciated!


Some Pics:
http://i.imgur.com/Shzjz30.jpg ( GPU-Z, hardware monitor )
http://i.imgur.com/UR7VmD9.png ( Catalyst )
http://imgur.com/5Za2F0e ( Speccy )