Asus X399 ROG STRIX PCI-E question

[Kapone33]

Hi I am researching a HEDT (affordable) build for a customer, everywhere I look it states that the X399 ROG STrix only supports 3 cards in the x16 slots. I see 4 PCI_E x16 slots on the board and the MB manual lists them at 16 or 8. I do not see any asteriks to state that any of the 16 slots share lanes with anything else. The reason I ask is because he wants to run 3 Asus Riser cards across the board as he does mostly video production and some rendering.

 

[EarthDog]

The X399-E Gaming, right?

So, three slots, three riser cards... what is the issue?

 

[Kapone33]

The X399-E Gaming, right?

So, three slots, three riser cards... what is the issue?

I am looking all over the internet. You see he wants to have a GPU in the first 16 slot and he wants to have 3 cards at 1 x16 and 2 at x8 of course split to have a total of 10 NVME drives (I am just building the machine) but I cannot find any information to confirm that the last x8 slot can be populated without losing any lanes.

 

[EarthDog]

Ok, that makes more sense.

From the looks of it, three PCIe slots (with shielding) are fed from the CPU. I'm wondering if non shielded slot is sourced from the chipset. I do not see anything in the specs that says lanes will drop.

Your best bet is to contact Asus and ask them as I do not see a block diagram of how things are wired for this board.

 

[Kapone33]

Ok, that makes more sense.

From the looks of it, three PCIe slots (with shielding) are fed from the CPU. I'm wondering if non shielded slot is sourced from the chipset. I do not see anything in the specs that says lanes will drop.

Your best bet is to contact Asus and ask them as I do not see a block diagram of how things are wired for this board.

That was my thought process. I like to start here first though.

Ok, that makes more sense.

From the looks of it, three PCIe slots (with shielding) are fed from the CPU. I'm wondering if non shielded slot is sourced from the chipset. I do not see anything in the specs that says lanes will drop.

Your best bet is to contact Asus and ask them as I do not see a block diagram of how things are wired for this board.

Ok this is getting interesting. I spoke to Asus; I asked the person on the phone if the last x16 supports PCI_E 3.0 x 8 and he confirmed that. I then asked him if it was connected to the CPU or chipset. He responded that it was connected to the chipset. I asked him "But does not the chipset only have 4 PCI-E 3.0 lanes" he responded that yes that was the case. I guess that this board might be wired differently with only 2 M2 slots because he held firm that the slot runs at PCI-E 3.0 x8. My thought is that this must be connected to the

 

[EarthDog]

My thought is that this must be connected to the

....... your though doesn't seem to be finished.

 

[Kapone33]

....... your though doesn't seem to be finished.

Yeah I got interrupted and hit enter by mistake. I was going to say that the slot must be connected to the CPU as there are only 6 SATA ports and 2 M2 slots on the board.

 

[EarthDog]

Maybe... I need to see a block diagram of it to be sure.

 

[basco]

4x PCIe 3.0 x16 (2x x16, 2x x8), 1x PCIe 2.0 x4, 1x PCIe 2.0 x1, 1x M.2/M-Key (PCIe 3.0 x4/SATA, 22110/2280/2260/2242), 1x M.2/M-Key (PCIe 3.0 x4/SATA, 2280/2260/2242), 1x U.2 (PCIe 3.0 x4)

 

[Kapone33]

This is taken directly from Anandtech's overview of the ROG board

"Additionally there is one PCIe x1 slot, a PCIe x4 slot, and full-length PCIe slot (x4). These slots distinguish themselves by not having the reinforcement". It would seem that Asus went out of the way to not put that in the literature. What I really need to see now is a reverse image of the board to see how the slot is wired.

 

[EarthDog]

View attachment 144182

that isnt in question.

This is taken directly from Anandtech's overview of the ROG board

"Additionally there is one PCIe x1 slot, a PCIe x4 slot, and full-length PCIe slot (x4). These slots distinguish themselves by not having the reinforcement". It would seem that Asus went out of the way to not put that in the literature. What I really need to see now is a reverse image of the board to see how the slot is wired.

I swear I said that, lol.

What does wiring have to do with it? The specs tell you what speed they are. See bacon's image (timely, lol).

Edot: to physically follow them?

 

[Kapone33]

View attachment 144182

I know that is what the manual says. It also goes on to say it only supports 3 GPUs.

4 x PCIe 3.0 x16 (single@x16, dual@x16/x16, triple@x16/x16/x8 mode)

Notice how it only goes to triple even though it clearly mentions 4 slots?

that isnt in question.

I swear I said that, lol.

What does wiring have to do with it? The specs tell you what speed they are. See bacon's image (timely, lol).

This is exactly why I am confused. seeing the back would be confirmation of whether it is wired as a x4 or x8 slot.

 

[EarthDog]

This is exactly why I am confused. seeing the back would be confirmation of whether it is wired as a x4 or x8 slot.

Its wired as x8. It's a 16x slot wired at x8.

 

[Kapone33]

Its wired as x8. It's a 16x slot wired at x8.

Excellent I am going pull the trigger but if you are wrong I am going to come looking for you

 

[EarthDog]

Excellent I am going pull the trigger but if you are wrong I am going to come looking for you

How many lanes does TR have?? Math should help this out too,no?

Also AMD GPUs only need x4 to run, Nvidia OTOH needs x8.

 

[Kapone33]

How many lanes does TR have?? Math should help this out too,no?

Also AMD GPUs only need x4 to run, Nvidia OTOH needs x8.

The specs for TR4 for is 66 total lanes of PCI-E 3.0 and 8 lanes of 2.0