PCIe 16x running at 8x?

[_Grid21]

I have a i7 4790, a Z87-a motherboard. I have quite a few expansion cards. So here is my issue, GPUz says my 980 Ti is running at x8 1.1. I was told supposedly on the OBS Discord that one of my expansion cards could be causing the 16x slot to run slower. I have in order, a 980 Ti, Fresco Logic PCIe to USB 3.0 card, my Elatgo HD60 Pro, and a SATA to PCIe expansion slot. How do I determine which PCIe card is slowing my GPUs PCIe lane down, OR is it that I am pushing the limit of lane support for my i7 4790? I have never run into or even thought about PCIe cards affecting each others lane speed. 

 

Please help me as this issue is affecting my streaming and gameplay as well. 

[Taf the Ghost]

3 minutes ago, _Grid21 said:

I have a i7 4790, a Z87-a motherboard. I have quite a few expansion cards. So here is my issue, GPUz says my 980 Ti is running at x8 1.1. I was told supposedly on the OBS Discord that one of my expansion cards could be causing the 16x slot to run slower. I have in order, a 980 Ti, Fresco Logic PCIe to USB 3.0 card, my Elatgo HD60 Pro, and a SATA to PCIe expansion slot. How do I determine which PCIe card is slowing my GPUs PCIe lane down, OR is it that I am pushing the limit of lane support for my i7 4790? I have never run into or even thought about PCIe cards affecting each others lane speed. 

 

Please help me as this issue is affecting my streaming and gameplay as well. 

You need to check your motherboard's manual. Probably having any card in the second x16 slot does it.

 

However, if it's a PCIe 3.0 board, then it doesn't matter. It takes a Titan V to populate a PCIe 3.0 x8 slot for bandwidth. And, even then, just barely.

[_Grid21]

6 minutes ago, Taf the Ghost said:

You need to check your motherboard's manual. Probably having any card in the second x16 slot does it.

 

However, if it's a PCIe 3.0 board, then it doesn't matter. It takes a Titan V to populate a PCIe 3.0 x8 slot for bandwidth. And, even then, just barely.

So I took my Elagto HD60 Pro out of the x16 slot and suddenly my GPU reads at the full lane. But that doesn't help me because I need the other 2 cards and I only have 3 PCIe x16 and 2 2.0 PCIe slots, so I am left with putting my other expansion cards in the x16 slots, but then that turns it from x16 to x8. So do I need to upgrade my motherboard to support the 4x PCIe cards I own?

[reniat]

11 minutes ago, Taf the Ghost said:

However, if it's a PCIe 3.0 board, then it doesn't matter.

if by "Z87-A" he means an asus z87-a, then yeah it's 3.0. @_Grid21 are you 100% certain that the PCI bus is your bottleneck at x8? Have you profiled your performance in different conditions to determine that? I'd be very surprised if it 8 gen 3 lanes wasn't enough.

 

Also, one thing to check quick is that the lane is set to gen 3 in the bios. You can have a gen 3 board and set the protocol to gen 1 or 2 in the bios, which will reduce your performance per lane. Make sure all slots are set to gen 3.

[_Grid21]

2 minutes ago, reniat said:

if by "Z87-A" he means an asus z87-a, then yeah it's 3.0. @_Grid21 are you 100% certain that the PCI bus is your bottleneck at x8? Have you profiled your performance in different conditions to determine that? I'd be very surprised if it 8 gen 3 lanes wasn't enough.

 

Also, one thing to check quick is that the lane is set to gen 3 in the bios. You can have a gen 3 board and set the protocol to gen 1 or 2 in the bios, which will reduce your performance per lane. Make sure all slots are set to gen 3.

The only option in the bios it would allow me was Auto, Gen 1, and Gen 2. I don't know why, but when I pulled the HD60 Pro out of the x16 slot, suddenly the 980 TI read "Bus Interface, PCIe x 16 3.0 @ x 16 3.0. But I was to plug the Elgato back into the x 16 slot, it reduces that reading down to x8 1.1

[Taf the Ghost]

6 minutes ago, _Grid21 said:

So I took my Elagto HD60 Pro out of the x16 slot and suddenly my GPU reads at the full lane. But that doesn't help me because I need the other 2 cards and I only have 3 PCIe x16 and 2 2.0 PCIe slots, so I am left with putting my other expansion cards in the x16 slots, but then that turns it from x16 to x8. So do I need to upgrade my motherboard to support the 4x PCIe cards I own?

See the other comment, but x8 or x16 is just maximum bandwidth. If it's running at PCIe 3.0 x8, it isn't effecting performance.

[Taf the Ghost]

1 minute ago, _Grid21 said:

The only option in the bios it would allow me was Auto, Gen 1, and Gen 2. I don't know why, but when I pulled the HD60 Pro out of the x16 slot, suddenly the 980 TI read "Bus Interface, PCIe x 16 3.0 @ x 16 3.0. But I was to plug the Elgato back into the x 16 slot, it reduces that reading down to x8 1.1

It defaults to PCIe 1.1?

[reniat]

2 minutes ago, _Grid21 said:

it reduces that reading down to x8 1.1

so it seems like your issue is standard being set to 1.1, not the lane count. I would maybe look to see if there is a bios update that will let you set gen 3 on those slots? (That board SHOULD have all it needs to support 3.0 out of the box, but bios updates on asus boards are easy enough so it might be worth a shot)

[Taf the Ghost]

1 minute ago, reniat said:

so it seems like your issue is standard being set to 1.1, not the lane count. I would maybe look to see if there is a bios update that will let you set gen 3 on those slots? (That board SHOULD have all it needs to support 3.0 out of the box, but bios updates on asus boards are easy enough so it might be worth a shot)

Something is wonky, for sure. It should split out the PCIe lanes, but he probably needs to crack out the manual and look at the lane diagrams.

 

I wonder if it's the Specific Cards. That capture card might be what's forcing it down to 1.1, rather than populating the slot.

 

@_Grid21 Try switching the Capture Card with one of the other PCIe cards into the larger slot. The Elegato card might just be forcing the 1.1 standard.

[_Grid21]

32 minutes ago, Taf the Ghost said:

Something is wonky, for sure. It should split out the PCIe lanes, but he probably needs to crack out the manual and look at the lane diagrams.

 

I wonder if it's the Specific Cards. That capture card might be what's forcing it down to 1.1, rather than populating the slot.

 

@_Grid21 Try switching the Capture Card with one of the other PCIe cards into the larger slot. The Elegato card might just be forcing the 1.1 standard.

I've put back all my PCIe cards and 2 of them are also in the x16 slots. When there is load on the GPU, it says PCIe x 16 @ x8 3.0. When there is no load, it defaults to 1.1. I've also changed the PCIe configs to Gen 3. ( http://prntscr.com/kmai0n Under Load) (http://prntscr.com/kmai66 Not under load)

[Taf the Ghost]

1 minute ago, _Grid21 said:

I've put back all my PCIe cards and 2 of them are also in the x16 slots. When there is load on the GPU, it says PCIe x 16 @ x8 3.0. When there is no load, it defaults to 1.1. I've also changed the PCIe configs to Gen 3. http://prntscr.com/kmai0n

Okay, so it's running at PCIe 3.0 x8. That's all you need. That should remove any of the bottlenecks you were running into.

[_Grid21]

1 minute ago, Taf the Ghost said:

Okay, so it's running at PCIe 3.0 x8. That's all you need. That should remove any of the bottlenecks you were running into.

The thing is, supposedly people on the OBS discord said that it was some how affecting OBS' performance for hardware encoding, but like, does that make any sense to you guys?

EDIT, if it's a x16 card, why is it going down to x8? Can you explain what this lane splitting and all the x's mean? I am a little out of touch in this area.

[Taf the Ghost]

5 minutes ago, _Grid21 said:

The thing is, supposedly people on the OBS discord said that it was some how affecting OBS' performance for hardware encoding, but like, does that make any sense to you guys?

EDIT, if it's a x16 card, why is it going down to x8? Can you explain what this lane splitting and all the x's mean? I am a little out of touch in this area.

Unless OBS is one of the stupidest programs in history, no, it sounds like ignorance.

 

x1, x4, x8 and x16. They're Lane counts. 1 Lane is a certain amount of data bandwidth. x4 is 4 lanes, so 4x the bandwidth. x8 is 8 lanes and x16 is 16 lanes. 

 

https://en.wikipedia.org/wiki/PCI_Express#PCI_Express_1.1

 

PCIe 3.0 x16 is the normal slot of for a Graphics Card. However, your card is probably only using about 5 lanes of bandwidth. The most demanding card you can buy (for 3k USD) is required to even need the 16 lanes. 

 

Now, the issue is that your CPU only has 16 Lanes that connect to the PCIe slots. If you have multiple cards in the slots, it has to split the Lanes. Your GPU is getting 8 lanes, while the rest of the cards are getting 1 lane, more than likely. That should be a total of 11 lanes being used. The GPU will be fine at PCIe 3.0 x8. That's 7.88 Gb/s of data. The issue, at PCIe 1.1, you were at 2 Gb/s of data. Some chunk of BIOS + card slot choices was defaulting to the lowest possible setting.

 

You've fixed that and it shouldn't cause any issues going forward.

[_Grid21]

25 minutes ago, Taf the Ghost said:

Unless OBS is one of the stupidest programs in history, no, it sounds like ignorance.

 

x1, x4, x8 and x16. They're Lane counts. 1 Lane is a certain amount of data bandwidth. x4 is 4 lanes, so 4x the bandwidth. x8 is 8 lanes and x16 is 16 lanes. 

 

https://en.wikipedia.org/wiki/PCI_Express#PCI_Express_1.1

 

PCIe 3.0 x16 is the normal slot of for a Graphics Card. However, your card is probably only using about 5 lanes of bandwidth. The most demanding card you can buy (for 3k USD) is required to even need the 16 lanes. 

 

Now, the issue is that your CPU only has 16 Lanes that connect to the PCIe slots. If you have multiple cards in the slots, it has to split the Lanes. Your GPU is getting 8 lanes, while the rest of the cards are getting 1 lane, more than likely. That should be a total of 11 lanes being used. The GPU will be fine at PCIe 3.0 x8. That's 7.88 Gb/s of data. The issue, at PCIe 1.1, you were at 2 Gb/s of data. Some chunk of BIOS + card slot choices was defaulting to the lowest possible setting.

 

You've fixed that and it shouldn't cause any issues going forward.

I feel silly for not knowing this since I study this stuff inside and out and I am a streamer myself, I knew something seem fishy but I wasn't sure what. Now, if you disable power saving stuff of the PCIe lanes, does that hold the slots at 3.0 instead of defaulting to 1.1 when not under workloads?

 

EDIT: How do PCI cards interact with the CPU and does that PCIe performance in any way? Granted PCI is a legacy technology, I am curious how that interfaces with the CPU. 

EDIT 2: I have a bigger question. Why aren't all the PCIe separate? Why do they have to share all the same lanes? And is this where AMD Ryzen 2 handles PCIe better than Intel 4th Generation? 

[Taf the Ghost]

6 minutes ago, _Grid21 said:

I feel silly for not knowing this since I study this stuff inside and out and I am a streamer myself, I knew something seem fishy but I wasn't sure what. Now, if you disable power saving stuff of the PCIe lanes, does that hold the slots at 3.0 instead of defaulting to 1.1 when not under workloads?

 

EDIT: How do PCI cards interact with the CPU and does that PCIe performance in any way? Granted PCI is a legacy technology, I am curious how that interfaces with the CPU. 

You'd need to look up the Chipset diagram for the platform to check. However, I'm fairly certain legacy PCI doesn't effect anything. PCIe should be completely separate from the PCI Bus.

 

On the power savings, no clue. Look up your motherboard's manual and read the PCIe settings closely. 

[_Grid21]

13 minutes ago, Taf the Ghost said:

You'd need to look up the Chipset diagram for the platform to check. However, I'm fairly certain legacy PCI doesn't effect anything. PCIe should be completely separate from the PCI Bus.

 

On the power savings, no clue. Look up your motherboard's manual and read the PCIe settings closely. 

Do new CPUs like Ryzen and Intel allow for more Lane bandwidth?

[Taf the Ghost]

7 minutes ago, _Grid21 said:

Do new CPUs like Ryzen and Intel allow for more Lane bandwidth?

On Mainstream? Not really. Ryzen has x16 to the Slots and x4 to a dedicated M.2 slot. Intel's recent ones have x16 to the Slots and this switching controller for more off the chipset.

 

But when it comes to PCIe lanes to the Slots, you have to go up to the HEDT platform to get more.

 

But, again, if the GPU is running at PCIe 3.0 x8, then it's perfectly fine. You are losing no performance that way.

[_Grid21]

2 minutes ago, Taf the Ghost said:

On Mainstream? Not really. Ryzen has x16 to the Slots and x4 to a dedicated M.2 slot. Intel's recent ones have x16 to the Slots and this switching controller for more off the chipset.

 

But when it comes to PCIe lanes to the Slots, you have to go up to the HEDT platform to get more.

 

But, again, if the GPU is running at PCIe 3.0 x8, then it's perfectly fine. You are losing no performance that way.

Alright, Thanks. I prefer coming here asking from people who know what they're talking about then randos from a Discord Server.

[Taf the Ghost]

3 minutes ago, _Grid21 said:

Alright, Thanks. I prefer coming here asking from people who know what they're talking about then randos from a Discord Server.

The problem you did have was the Elegato was driving down the Lane Spec for some strange reason. That would have impacted performance.

[Mick Naughty]

Why not just put the capture card in another pci lane, one that runs off the chipset. Same thing I did but I’m running a pair of gpu’s. So I don’t have lanes to spare.