PCIe help required [discussion]

Sonikks

Sonikks

Sonikks

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Joined
8 Jun 2019
Posts
9
Hello all,

My first post here as I've just signed up.

I'm tripping over myself during research on PCIe lanes & my motherboard's capability. I could really do with some clarification.

Here's the bulk;

I recently purchased and built my first PC build. Here are the specs first of all;

d0frpvy.png


I'm a content creator on Youtube and I have a large number of devices connected to my system which include; 4 x Nintendo DS capture cards (USB) which are connected via an Inateck USB 3.0 PCIe expansion card, 4 x USB sound cards (no issue with those connected to Motherboard) as well as a microphone via USB & wireless mouse/keyboard receiver. USBs are not an issue but the PCIe lanes are causing some.

I am concerned about the amount of bandwidth my PCI lanes are receiving. My Nintendo DS/3DS capture cards can sometimes lag or drop frames. As a way of troubleshooting, I used one system plugged in and I still had the issues which have led me here to troubleshoot my PCIe bandwidth capability. As the next main series Pokémon games are coming to the Switch, I am going to be investing in an Elgato HD 60 Pro which installs via PCIe and uses 1x lane however before I do so, I want to ensure my CPU is not going to bottleneck my connections.

According to my calculations based on my CPU I have 20 lanes available, 16 of which are being used by my GPU, 1 lane is being used by my Inateck USB 3.0 card and a number is being used by my SATA connection to my SSD.

- Can someone help me calculate my lane usage?

- Why do my systems lag at random intervals, is it because I'm over my CPU's 20 lane allowance?

- Why does Speccy state that they're "in use" when nothing is installed into them?

- Am I okay to further add PCIe cards without bottlenecked connections?

Here is my PCIe data from Speecy;

Zj6QTPF.png


Notes

My BIOS was recently flashed to the most recent version.
My power supply is 850 watts if that helps.
Every component was purchased brand new.

Thanks in advance, let me know if you require further screenshots or information on my system.
 
Welcome aboard.

16 of CPU's PCIe v3.0 lanes go permanently to main x16 slot.
Four other lanes are shared between that second mechanically x16 but electrically x4 slot and M2_1 slot.
Those can't be used for anything else.

x1 slots are all connected to chipset and are PCIe v2.0 slots with half the bandwidth of v3.0 per lane. (500MB/s)
Chipset itself is connected to CPU using four v3.0 lanes, making total of ~4GB/s.

With Ryzen being SOC design some USB ports should be connected directly to controller in CPU and hence don't use bandwidth between chipset and CPU.
But motherboard specs don't tell that.
Not sure if manual would be more precise.
 
EsaT said:
Welcome aboard.
Click to expand...

Thank you & thanks for the reply

EsaT said:
16 of CPU's PCIe v3.0 lanes go permanently to main x16 slot.
Four other lanes are shared between that second mechanically x16 but electrically x4 slot and M2_1 slot.
Those can't be used for anything else.

x1 slots are all connected to chipset and are PCIe v2.0 slots with half the bandwidth of v3.0 per lane. (500MB/s)
Chipset itself is connected to CPU using four v3.0 lanes, making total of ~4GB/s.

With Ryzen being SOC design some USB ports should be connected directly to controller in CPU and hence don't use bandwidth between chipset and CPU.
But motherboard specs don't tell that.
Not sure if manual would be more precise.
Click to expand...

I installed the USB 3.0 expansion card into my 2nd 16x PCIe slot & I have to say, the difference is very, very noticeable. The connection to the Nintendo DS capture cards seems much more stable, though not perfect. So I have my GPU & then my USB expansion card taking up both of the x16 slots, which is fine.

If I understand correctly, my x1 PCIe v2.0 slots have too low bandwidth to handle the demands I want from my system. My question is, is the bottlenecking coming from my CPU or the motherboard's PCIe slots still not giving me enough?

I'm guessing I'm requiring an upgrade but I need advising on which component precisely (if not both).
 
If capture cards have own hardware encoder they shouldn't need that much bandwidth, or even CPU power.
But bandwidth of single USB3 port indeed matches that of one PCIe v2.0 lane.
So four capture cards connected to controller in that single lane could cause some momentary hiccups.

Could try moving one or two of capture cards to motherboard's USB3 ports.

Apparently you have SATA SSD, because NVMe SSD likely shouldn't usable with PCIE4, but that would be more than enough to store multiple compressed video streams.
Again if you have only HDD, that could struggle some.
 
EsaT said:
If capture cards have own hardware encoder they shouldn't need that much bandwidth, or even CPU power.
But bandwidth of single USB3 port indeed matches that of one PCIe v2.0 lane.
So four capture cards connected to controller in that single lane could cause some momentary hiccups.
Click to expand...

I now have two inserted into my Motherboard and two in the PCIe card. Only the ones installed in the PCIe card are stuttering occasionally. I have now solved this issue upon research & your suggestion. It would appear that the Inateck USB 3.0 PCIe expansion card requires a PCIe 2.0 port whereas unfortunately according to my Motherboard's manual & website, my slots are only 1.0. That is extremely disappointing as that means I will not be able to purchase & install an Elgato HD60 Pro as that also requires a minimum of 2.0. I won't be able to record without frame drops with that bandwidth bottleneck. I'm just happy I have that answer & I will be looking to sell this current one & upgrade to another in the next month.

Just curious but is there some sort of bottleneck on the motherboard's USB hubs? If I plug in all of my USBs that I need, some of them will not work. It seems there's a power issue. I'd be curious to understand more on that.

Thank you for your help by the way.
 
EsaT said:
B450's (and even B350's) PCIe lanes are v2.0
https://en.wikipedia.org/wiki/Socket_AM4#Chipsets
Though BIOS might have setting for forcing them into v1.0 mode.

If BIOS is older might be worth of trying newer.
There might be some kind compatibility improvements.
Click to expand...

You're correct, I completely misread the manual. I feel like an idiot now.

Then I quite frankly have no idea what's the issue. I'm guessing it's the CPU bottlenecking with the amount of PCIe lanes it can handle. What do you think? According to the manual, it can support 20 lanes.

I have the most recent BIOS update
 
IIRC have sometimes seen PCI express compatibility improvements in BIOS upgrade descriptions, so checking how old BIOS is woudl be one thing.
 
Just something that probably has nothing to do with it - it says there's 24GB RAM in the system and it's in dual channel. What kind of setup is it? 2x8GB sticks + 2x4GB sticks or other?

Asking because it's unusual (not impossible) for someone with their first PC to have that number, instead of 8, 16 or 32GB for example. On the off-chance it's actually a problem and not intentional.
 
Danny75 said:
Just something that probably has nothing to do with it - it says there's 24GB RAM in the system and it's in dual channel. What kind of setup is it? 2x8GB sticks + 2x4GB sticks or other?

Asking because it's unusual (not impossible) for someone with their first PC to have that number, instead of 8, 16 or 32GB. On the off-chance it's actually a problem and not intentional.
Click to expand...

I didn't even notice that. I have 3 x 8GBs. Is that bad? Please advise.

https://imgur.com/i4VoyDl

Here's a picture of the RAM. RAM was super cheap so I thought I'd get as much as possible. I do a lot of multitasking, streaming, encoding, rendering, stream deck etc.

Just doing a quick check, it would seem like pairing them in dual channel is much better. I'm still learning as I've been a laptop user for over 10 years. I should probably get another stick.
i4VoyDl

i4VoyDl
 
Sonikks said:
I didn't even notice that. I have 3 x 8GBs. Is that bad? Please advise.
Click to expand...

I wouldn't know how bad as I've never tested it nor am I very informed about it. Just know it can hinder performance. In what way, might vary from platform to platform or specific motherboard, maybe having three sticks could drop them all to single channel, or keep two in dual channel but one in single, don't know.



Sonikks said:
Just doing a quick check, it would seem like pairing them in dual channel is much better. I'm still learning as I've been a laptop user for over 10 years. I should probably get another stick.
i4VoyDl

i4VoyDl
Click to expand...

Might be an idea to take out one stick to test, leaving the remaining two in the optimal slots for primary dual channel configuration (motherboard manual should tell you).
 
Using me as a guinea pig :P

I'll remove a stick & report back. This PC malarky is giving me a headache. Getting there bit by bit. The store had a 3 4 2 offer on RAM, I thought I snagged a bargain.
 
Sonikks said:
Using me as a guinea pig :p

I'll remove a stick & report back. This PC malarky is giving me a headache. Getting there bit by bit. The store had a 3 4 2 offer on RAM, I thought I snagged a bargain.
Click to expand...

Be sure to remove the correct ram stick when you test or you may just leave two in the same channel and be running single channel.

Generally if your sticks have an empty slot between them then you are good, but consult your motherboard manual.
 
Marak said:
Be sure to remove the correct ram stick when you test or you may just leave two in the same channel and be running single channel.

Generally if your sticks have an empty slot between them then you are good, but consult your motherboard manual.
Click to expand...

Thank you, I did that. Channel one is slot 1 & 3 for my machine. According to some late night research, Ryzen CPUs are better suited to a single channel of RAM being utilised rather (2x8GB) rather than (4x8GB) both being covered.

It hasn't made much difference in terms of the frame rate drops on my devices. My two devices connected to my Motherboard work just fine but the ones installed on the PCIe expansion card are still struggling. I should note that the expansion card is connected to my PSU via a SATA cable so I know there is sufficient power.

Does anyone have any other advice/ideas? I keep reading up on sufficient bandwidth utilisation via the CPU as the motherboard seems to be able to handle everything else just fine. Could the amount of lanes/USBs installed be too much for my CPU?
 
Further to what EsaT said earlier in the thread about the controller on the expansion card, the Inateck appears to have only one controller for all five USB ports, whereas there is a Startech card for example that has four controllers, one for each of four USB ports and is better at avoiding drops. This chap goes into it @2:43

 
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