Solved! Seeking Confirmation On PCIE Bifurcation Support

[TryingToVirtualizeStuff]

Hello,

My company plans on building a powerful system to house a bunch of PCIE cards (for video recording, analysis, playout, etc), and I wanted to confirm that the following configuration will work (as I'm pretty sure it will but wanted to double-check).

I plan on using the following motherboard: Asus Pro-WS-WRX80E-SAGE-SE-WIFI - https://www.asus.com/us/Motherboards-Components/Motherboards/Workstation/Pro-WS-WRX80E-SAGE-SE-WIFI/

...to bifurcate one of the PCIE 4.0 x16 slots to two PCIE 3.0 x8 slots (to be populated by two Aja Kona 5's): https://www.aja.com/products/kona-5

Given that both cards are the same model, rated for the same bandwidth (PCIE 3.0 x8), I'd imagine there'd be no problem whatsoever splitting the PCIE slot, but I just wanted to be absolutely certain there are no issues with doing this.

If everything looks like it should work, does anyone have any recommendations for riser cards?

I assume the following card: https://www.serverparts.pl/en/rsc-d2-66g4-i6982

...should work (along with some sort of riser bracket like the one seen here): https://www.in-win.com/en/peripherals/pci-e-riser-cable-4-bracket

...but if anyone knows of a bracket (or a riser + bracket) that could be added to the following chassis:

SC747BTQ-R2K04B | 4U | Chassis | Products | Supermicro

747BTQ-R2K04B

www.supermicro.com

...that would be greatly appreciated.

Thank you,
Nelson

 

[Justinus]

From the manual:



It would appear ASUS only exposed two modes for the slots on this board - 16x and 4x/4x/4x/4x. No mention of 8x/8x mode support whatsoever.

Historically ASUS hasn't been good about exposing bifurcation settings on supporting platforms. You might want to look at other options.

 

[TryingToVirtualizeStuff]

From the manual:

View attachment 57207

It would appear ASUS only exposed two modes for the slots on this board - 16x and 4x/4x/4x/4x. No mention of 8x/8x mode support whatsoever.

Historically ASUS hasn't been good about exposing bifurcation settings on supporting platforms. You might want to look at other options.

Hello Justinus,

It's crazy that they support x4+x4+x4+x4 but from the looks of things, don't support x8+x8 (or at least I couldn't find anything).

That said, when I looked at their BIOS settings, I noticed that you can set the bandwidth (for a PCIe slot) to either Auto or x16 (which would leave me to believe x8 should be supported).

But you're right, there's nothing in the manual that states that x8 is supported, though in all fairness what you displayed above is all the information the manual has about PCIe bifurcation.

That said, a big thanks for pointing this out.

Nelson

 

[Leeea]

...to bifurcate one of the PCIE 4.0 x16 slots to two PCIE 3.0 x8 slots (to be populated by two Aja Kona 5's): https://www.aja.com/products/kona-5

I am 90% sure that with the board you picked, it will not work.

I went through the entire manual:

https://dlcdnets.asus.com/pub/ASUS/mb/SocketTRX4/Pro_WS_WRX80E-SAGE_SE_WIFI/E19401_Pro_WS_WRX80E-SAGE_SE_WIFI_UM_V2_WEB.pdf

and at no point did it say anything about x8 bifurcation.

That board does however straight up have 7 PCIe slots.

 

[TryingToVirtualizeStuff]

I am 90% sure that with the board you picked, it will not work.

I went through the entire manual:

https://dlcdnets.asus.com/pub/ASUS/mb/SocketTRX4/Pro_WS_WRX80E-SAGE_SE_WIFI/E19401_Pro_WS_WRX80E-SAGE_SE_WIFI_UM_V2_WEB.pdf

and at no point did it say anything about x8 bifurcation.

That board does however straight up have 7 PCIe slots.

Thanks for looking into this.

That said, ideally I'm trying to fit 8 PCIe cards into the motherboard (so 7 slots is just a little too low).

I know I can get more PCIE slots with a dual socket EPYC, but don't want to that route due to the hugely increased price.

Thanks,
Nelson

 

[Justinus]

I would look at alternative brands like asrock, they have supported flexible bifurcation options that asus has not on other platforms.

 

[sdifox]

I don't think there is room for 8 pcie slots.

 

[tcsenter]

Use this as a guide, I see nothing about support for PCI-E adapters: https://www.aja.com/support/kona-pc-system-configuration

 

[BonzaiDuck]

As someone said, ASUS hasn't been wonderful supporting on-motherboard bifurcation.

However, because I want two NVME cards and only want to use the same PCIE-slot for them, I found an adapter card which does it anyway. Don't know if that would fix your problem, because it depends on the cards you need and the cards that are available for that need.

 

[TryingToVirtualizeStuff]

As someone said, ASUS hasn't been wonderful supporting on-motherboard bifurcation.

However, because I want two NVME cards and only want to use the same PCIE-slot for them, I found an adapter card which does it anyway. Don't know if that would fix your problem, because it depends on the cards you need and the cards that are available for that need.

Hello BonzaiDuck,

Thanks for the input (as I'm certain an active solution would've worked for me). Ultimately I decided to select different components so that the extra PCIe slot wasn't necessary.

Furthermore, given that it's for a company build, I didn't want to chance something not working/fitting (as the system is around $60,000.00 - $62,000.00 and having to deal with a problem after the fact, would be a major headache).

Regards,
Nelson

 

[tcsenter]

Your company doesn't want the chance of some 'troubles' (that you can get blamed for), then go with one of the prebuilt workstations already supported or tested by AJA. Update all the firmwares and install the cards yourself. Might not reduce the chances of troubles but you get full support from at least one company (AJA) rather than 'this motherboard/configuration isn't on our supported/tested list, contact them' finger-pointing contest that often happens.

You could buy it configured with less (or no) RAM, drives, then add them yourself since the OEMs always charge way more for RAM and drives than you can buy them for. Seriously, If my company asked me to build this, I would decline unless I happened to have some approximate experience.

 

[TryingToVirtualizeStuff]

Your company doesn't want the chance of some 'troubles' (that you can get blamed for), then go with one of the prebuilt workstations already supported or tested by AJA. Update all the firmwares and install the cards yourself. Might not reduce the chances of troubles but you get full support from at least one company (AJA) rather than 'this motherboard/configuration isn't on our supported/tested list, contact them' finger-pointing contest that often happens.

You could buy it configured with less (or no) RAM, drives, then add them yourself since the OEMs always charge way more for RAM and drives than you can buy them for. Seriously, If my company asked me to build this, I would decline unless I happened to have some approximate experience.

Hello TCSenter,

Unfortunately, I didn't know at the time what sort of Hell I'd have to go through to get this system configured.

Now that I do, I assure you, I will never do this again.

That said, I work at a small company and will be the primary user of this system (for video/IP testing).

As for an AJA system, none of AJA's systems would work for my purposes.

I needed a system to do:

- 8K PSNR testing
- SDI (up to 8K) playout, recording and analysis
- ASI playout, recording and analysis.
- 2022-2 playout, recording and analysis.
- 2022-6 (up to 8K) playout, recording and analysis.
- 2110 (up to 8K) playout, recording and analysis.
- Act as an automation server, file server, VM server.

I was able to get all of that with a single system (at around $61,000.00). I'm still missing software (which will cost around $5,000.00 - $20,000.00 extra depending on what software I use), but all the hardware is there.

Just for your information, buying a preconfigured box to only do 8K PSNR (from a company like VideoClarity - which is an industry standard), costs around $82,000.00.

The box itself is running an old i9 (from 2018 with 8 cores and 64GB of RAM).

Or another example would be 2022-6 playout and analysis box from Sencore (this wouldn't include recording). A box to do that costs nearly $76,000.00.

Lastly, all of the hardware and software that I use at my company is old and barely works or freeware (which makes my job very difficult). With this box, my job will be made much easier.

That said, I've been designing this system since November of last year, going back and forth with all sorts of software vendors, hardware vendors and system builders. All told, I've probably spent around 250 hours working on this (quite a bit of that was off the clock).

Never again...

But the quote for the system was forwarded to upper management today (thankfully), and I'm finally done.

Regards,
Nelson