Asus Rampage II Extreme with 2(two) m.2 PCIe adapter cards

Hello everyone! First of all, congratulations for the Great forum!

Here is my preliminary notes:
My motherboard is Asus Rampage II Extreme (stock 2101 bios) and has three PCIe 2.0 x16 slots, which can be configured to work as x16 x8 x8.
Recently I bought a Samsung 950 Pro, 256 GB and a PCIe 3.0 x4 adapter for M.2 NGFF PCIe SSD. When the adapter is installed on the third (white) PCIe x16 slot, everything working fine: Samsung 950 Pro is recognized by the bios and now it’s the system drive. But if I put the adapter card on the second (blue) PCIe x16 slot, the video card (installed on first PCIe x16 slot) is disabled, there is no video signal.
Since, I have another spare Corsair MP500 m.2 SSD, I would like to make good use of the second PCIe x16 slot, if it is possible.
I did some research before posting here and the best description of my case, I found on an Adaptec Support page:

So, here is my question: Is there a way to force the second PCIe x16 slot to work as "general purpose" PCIe slot and not as "graphic slot" only? Do I need bios modding?

Any suggestion?
If my question is not in the right topic, a moderator of the forum, can move it to the right place.

@veselinbg :
Welcome to the Win-RAID Forum! I am sorry for my delayed reply.

According to my knowledge this can only be done by the mainboard manufacturer and not by the user.

Dieter (alias Fernando)

@veselinbg :
Try to enter on bios -> Advanced -> Chipset -> NorthBridge Chipset Configuration -> PCIe Selector

And change from "AUTO" to "x16 x1 mode".

Please let us know if this works.

I already done this, now the PCI selector is set to “x8 x8 mode”. Unfortunately, this doesn’t help.
I didn’t try to set it to “x16 x1” mode, because I want to use the third PCIe x16 slot at the highest possible speed.