ASUS Maxim VIII Hero - Help - PCIe Bus lanes 2x16(8x8 Dual) and 1x4 PCIe

[BLAs68]

Of course not what made you think that?

 

[ATMINSIDE]

Of course not what made you think that?

This...

Going to pop it into x8 dual sli mode and compare the performances.

 

[Johan45]

Are you running an M.2 NVMe SSD ?

 

[BLAs68]

Are you running an M.2 NVMe SSD ?

Didn't know they came out until you posted. I wouldn't have a lane to use with the x16 slot being used. No m2 for this mobo in the future.

I have the standard Samsung Pros.

 

[ATMINSIDE]

Didn't know they came out until you posted. I wouldn't have a lane to use with the x16 slot being used. No m2 for this mobo in the future.

Yes, you would have an x16 slot available.
M.2 on Z170 pulls from the chipset, not the CPU.

 

[Johan45]

Typically the 2 x8 slots share bandwidth and the last x4 plus the pcie 1x slots share but that's also where the m.2 would travel , that's what I understood anyway. That's why I asked, maybe it was interfering with his x4 slot.

 

[ATMINSIDE]

Here's the block diagram for Z170, the M.2 and such pull from the twenty lanes on the chipset:

 

[Johan45]

So where do the x1 slots run from ? IF you have two cards for the 16 lanes that would mean all other PCIe interface including the last x4 runs from the chipset no?

 

[EarthDog]

That is correct as much as I recall...

 

[ATMINSIDE]

So where do the x1 slots run from ? IF you have two cards for the 16 lanes that would mean all other PCIe interface including the last x4 runs from the chipset no?

Correct, the CPU lanes are only used for the main slots.
Depending on the board's layout it may specify "PCIe 3.0 x4 (slot 3) is disabled if two graphics cards are installed" or something similar.

 

[Johan45]

The maxhero's last x4 shares with the x1 and sata that's why I suggested the NVMe

 

[ATMINSIDE]

The maxhero's last x4 shares with the x1 and sata that's why I suggested the NVMe

If the last x4 slot shares with the x1, SATA, and M.2 then there's why it wouldn't detect a GPU.

 

[Johan45]

Bingo http://www.manualslib.com/manual/978204/Asus-Maximus-Viii-Hero.html?page=36#manual

 

[BLAs68]

Haha, sorry about that, I meant to say x8/x8 dual mode. The cards will default to that regardless of sli.

 

[BLAs68]

When I put in the GPU that time, I had a sound card in the x1 slot but it was x1_1 which according to that manual page shouldn't of counteracted the GPU being inserted to x4 slot.

Correct me if I'm wrong or didn't read the diagrams right, but I think the GPU wasn't detected because the GPU in the x16 lane hogged up all the CPU lanes.

I feel they didn't show that the x4 lane could be used in my GPU setup because it was either 1 at x16 mode or 2 at x8/x8 mode and its inefficient to use the x4 slot since it would have to be x8_2/x4.

The Pascal GPU didn't go to dual mode because it can't with an x4 lane so the GPU for PhysX wasn't detected.

 

[EarthDog]

PhysX can and does work in a 4x slot though... its multi GPU from NVIDIA that needs 8x+.

 

[BLAs68]

Definitely for sure, but was the problem of the GPU at the x4 not being detected a result of the GPU at the x16 using all the lanes?

 

[EarthDog]

Its the way the board is setup. Some boards have more PCIe switches on it and can route more lanes to more PCIe slots.