X99 , Noctua D15 and PCIE3.0 x16 ¿problems?

[Markpat]

Hello, I am going to buy one x99 gaming 7 and a 5820k (28 lane cpu), I already have one noctua D15 which I would like to use with the new mobo. the problem is that Noctua have  told  the that the D15 is going to block the first PCIE 3.0 x16, so I need to connect the graphics card in the next 3.0 x16 slot which is PCIE_2 3.0 x16.

I am going to  install only one gpu.

The problem is I don't know is the gpu will work in PCIE_2 3.0  x16 mode or it will work at 3.0 x8 mode due the 28 lane cpu.

The manual isn`t clear because It recommends the first slot for 1 gpu and the other descriptions are for SLI 40 and 28 lanes. But I would like to know for sure  if the gpu will work 3.0 x16 or x8 due the 28 lanes ,in the PCIE_2 with all the others clear

Thanks for your time.

[zil_jay]

I have a feeling Noctua will be processing a lot of returns.  The Noctua D15 will definitely block the first PCIE slot in this motherboard.  The thing is the size of rhode island. On the bright side,  at least you can still plug in your high rise memory modules!  Who needs graphics cards anyway?

In all seriousness, from everything I've read, installing the card in the second slot (paired with the 5820k) will cause the card to operate at x8.  I wish I could find the article I found - it spelled it out pretty cut and dry (If I can find it again I'll post it).  The performance hit is supposedly negligible though.  The principle is still unacceptable, IMO.   

[H4X3R]

i have the scythe mugen max with my x99 ud5 and it blocks the first x16 slot. I am now forced to run my gtx 970 @ pcie gen 3 x8, which is fine by me.
There is no performance difference between x8 and x16 at the moment.