[SOLVED] Practical limits of PCI-E buss devices?

Jun 24, 2020
27
5
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New to multipurposing the PCI-E buss and am wondering just how far I can push simultaneous video i/0 and storage on a ASUS Prime x-570 Pro motherboard?

Here's my current setup:

⦁ Windows 10 Pro 1903 (OS Build 18362.900)
⦁ ASUS PRIME X570-PRO AM4 ATX Motherboard
⦁ AMD RYZEN 9 3900X 12-Core 3.8 GHz Processor
⦁ No overclocking applied
⦁ 2 x Sabrent Rocket Q 1TB NVMe PCIe M.2 2280 Internal SSD High Performance Solid State Drive R/W 3200/2000 MB/s
⦁ #1 is bootable with Windows 10 Pro 1903 (OS Build 18362.900) and all updates are installed. (this uses the PCI-E bus)
⦁ #2 is cache and scratch for DaVinci Resolve Color Correction (I think this uses the Chipset bus)
⦁ Samsung EVO 860 1 TB SSD for misc. storage
⦁ Team T-FORCE VULCAN Z 32GB (2 x 16GB) 288-Pin DDR4 SDRAM DDR4 3200 (PC4 25600)
⦁ RAM clocked to 3200 MHZ via DOCP profile (rated RAM speed)
⦁ Thermaltake Toughpower GF1 750W 80+ Gold SLI/Crossfire Ready Modular Power Supply 1
⦁ NVIDIA GEFORCE GTX TITAN X (Maxwell) 12GB GDDR5
⦁ 1st PCIe 4.0 x 16 slot)
⦁ Nvidia 451.48 driver
⦁ Blackmagic Design Intensity Pro 4k Capture & Playback Input/Output Card
⦁ 2nd PCIe 4.0 x 16 slot

I have as of yet to determine my main RAID array for loading color correction and video editing jobs.

Being that you NEVER have enough high speed storage for video color correction and editing, I have been exploring both the QNAP TR-004 4 bay USB 3.20 type C RAID (Level 5) and the ASUS Hyper M.2 X16 PCIe 3.0 X4 Expansion Card V2 which supports 4 NVMe M.2 cards.

The QNAP would probably be sufficient for most situations, but the ASUS card would be pretty sweet for 4K and even above, even if it is far less capacious (poentially) than the QNAP.

Do you see my concern here?

When do you start starving the PCI-E pipeline?



 
Solution
OK. What about a practical limit on how many devices you can place on the PCI-E bus before i/O degrades?
Depends entirely on total aggregate bandwidth of attached devices, concurrency of IOs and jitter sensitivity of whatever you are doing. For DAW work, you can have 1% bus utilization and already have issues when your timing-critical audio packets end up behind large packets from an SSD. Similar issues can happen with VR kits when different position sensors attempt to send data all at the same time, some packets may get dropped unless every device is on a separate USB root hub despite each individual device needing an insignificant fraction of USB's bandwidth.

InvalidError

Titan
Moderator
OK. What about a practical limit on how many devices you can place on the PCI-E bus before i/O degrades?
Depends entirely on total aggregate bandwidth of attached devices, concurrency of IOs and jitter sensitivity of whatever you are doing. For DAW work, you can have 1% bus utilization and already have issues when your timing-critical audio packets end up behind large packets from an SSD. Similar issues can happen with VR kits when different position sensors attempt to send data all at the same time, some packets may get dropped unless every device is on a separate USB root hub despite each individual device needing an insignificant fraction of USB's bandwidth.
 
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Solution
Jun 24, 2020
27
5
45
Well, that would explain some velocity errors of the playhead I am seeing in the Fairlight section of DaVinci Resolve 16 Studio! That is what concerns me; exacerbating this issue.

Frankly, I think Blackmagic has bitten off more than anyone can chew and integrating a DAW, NLE, Crash editor, Node based compositing system AND a Color correction system in ONE software package is just asking for issues on anything other than dedicated workstation-grade computers.

Looks like I have pushed the PCI-E bus as far I should and will probably go for the USB C attached storage option.

Thank you!