MP 1,1-5,1 TB 3, cMP & eGPU

[Noobraino]

Hey guys,

I recently bought a Flashed Thunderbolt 3 Gigabyte Titan Ridge Card for cMP and i got a couple of questions.

(a) First i know that i won’t be able to have the full speed of TB3 due to the limitation of the PCI-e 2.0 lane of the cMP but what kind of speed rate you guys think i should get?
I made a quick test of the card upon installed with the Black magic Disk Speed Test and i get around ~360 MB/s read and write with a G raid external enclosure hooked up in TB3.

(B) Second question, since now i get TB3 connectivity, is eGPU a possibility for the cMP or the speed limitation will be too great for the GPU to work full speed and properly?

Thanks a lot.

 

[MarkC426]

I would say no-go.
That 360mb/s isn’t fantastic, 250 from sata 2 port, 500 from pcie card.
AFAIK the motherboard does not have any support for TB (reading the info for titan ridge - it is to upgrade a TB2 capable mb to TB3).

 

[Noobraino]

Thanks for the reply.

Well the guy who sold it to me is advertising teh card to be working and used in a MacPro 5.1.
The cards work as you’ll see in the picture, it is pretty much plug and play.
I’m just wondering given it is in a PCI-e Slot 2.0 how much speed sacrifice I should have.

 

[MarkC426]

Well that IS interesting......need some input from someone with more knowledge on this ?

If you have some time have a look here (52 pages)

testing TB3 AIC with MP 5,1

The good folks at egpu.io have had some encouraging results with the latest Gigabyte TB3 add-in card and will be testing in MP 5,1. Will be very interesting to see the results. Hat tip to @itsage. [edit] to correct link

forums.macrumors.com

 

[bsbeamer]

Why do you need to use an eGPU with this card and MP5,1? Storage arrays are the main target for the TB3 hack. Four PCIe slots can house GPU or multiple GPUs. Beyond that, there are PCIe expansion boxes to add additional external PCIe slots that work natively.

 

[Noobraino]

@bsbeamer because i want to know if i could mount 4 GPUs on the cMP for example.

I will rig one of my 2 cMP with dual Radeon RX580 and i was wondering if i could go 4 RX580 by adding an eGPU box with 2 slots.

My main concern is that so far the speed i get with the card is low so it would be a bad idea in that case.

That is why i asked what could be a potential/normal data rate transfer with this card given it is in a PCI-e 2.0 slot.

 

[bsbeamer]

See this if your goal is actually getting a significant number of GPUs working with MP5,1:

Cubix Corporation's Family Of PCIe Expansion Units.

Xpanders + graphics or GPU cards are the easiest and most affordable way to boost the compute power of any modern workstation or rackmounted host station.

www.cubix.com

Some tests from back in the day:

Mac Pro with FIVE GPUs!

real world speed test results for performance minded Macintosh users

barefeats.com

You can also basically recreate this on the ultra cheap if you use PCIe extension ribbon cables and an external PSU. Can get up to 4x GPUs in one MP5,1 using all slots.

 

[Noobraino]

@bsbeamer thanks for this i’ll read it.

 

[MarkC426]

You will need a bank loan for a cubix expander.

 

[Noobraino]

Yeah, Cubix doesn't seem to be an option to be honest. It would be much simpler to hook up a cheaper eGPU Box if I can figure out if my card is defective or not and what kind of speed I can get out of it.

 

[MarkC426]

What applications are you wanting this setup for?

 

[bsbeamer]

CUBIX is not the only player in the PCIe expansion space. Dynapower Netstor systems work fine for some people. Even StarTech makes a cheap PCIe expansion box. Lots of options if you search...

 

[MarkC426]

These cheaper options won’t give you full speed x16 pcie though, will they.
Hence the cost of the Cubix.

 

[bsbeamer]

Dynapower has four PCIe x16 units and they’re really not that expensive if you’re looking for 4 GPU expansion with PSU.

If that’s too expensive, as suggested earlier, build your own with ribbon cable extensions and make a franken build with an external PSU. It’ll be a mess but does the trick, usually.

Ultimately you’re switching the unit between whatever your connected to. Your not magically making eight x16 PCIe slots in an MP5,1 regardless of expansion being used.

 

[joevt]

Connect a Netstor NA255A so you get four PCIe 3.0 x8 slots. Use one slot to get full speed Thunderbolt 3 (increase speed from 1600 MB/s to 2750 MB/s). https://www.bhphotovideo.com/c/product/980261-REG/dynapower_usa_na255a_xgpu_netstor_6_slot_pcie.html

Other options: B&H Photo list of PCIe expansion chassis options

 

[bsbeamer]

Slight difference between NA255A and NA255A-XGPU.15, make sure you choose the one that meets your needs if purchasing:

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dynapowerusa.com

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[Noobraino]

Guys I really appreciate that you replied to my questions.

The only thing that is a road block right now is figuring out if the data transfer rate (360MB/s) I get with the card I bought is normal due to the cMP PCI-e slots configuration or that my card is defective and I should get a higher data rate transfer.

Obviously all these eGPU solutions that you guys suggested are great but will be money thrown in the fire if I can only have the 360MB/s Data Rate Transfer via the Thunderbolt3 connection.

 

[MarkC426]

Can’t really comment on the TB3 pcie card (as it’s not really supported, maybe why the speed is low).
But with a 2.5” SSD pcie card you get sata 3 speeds of 500mb/s (even more when there in a raid).

Does your raid have any other connections to try, i.e. usb?

 

[joevt]

Guys I really appreciate that you replied to my questions.

The only thing that is a road block right now is figuring out if the data transfer rate (360MB/s) I get with the card I bought is normal due to the cMP PCI-e slots configuration or that my card is defective and I should get a higher data rate transfer.

Obviously all these eGPU solutions that you guys suggested are great but will be money thrown in the fire if I can only have the 360MB/s Data Rate Transfer via the Thunderbolt3 connection.

I'm not sure why you expect more than 360 MB/s. The specs say 440 MB/s max.

Show us the info for the AHCI controller pci1b21,625. It's probably some low bandwidth raid controller PCIe 2.0 x1 or something like that.
Then show us the info for the drives you have installed in the RAID. The RAID only supports two drives. If you have two 7200 RPM HDs, then 360 MB/s seems reasonable.

The RAID has a USB 3.1 gen 2 port. Did you try that instead of Thunderbolt? I don't expect to to give better performance. Show us what USB to SATA controller it uses when you connect using the USB-C port.

 

[universenz]

On a stock Mojave install (no Opencore) I have the "flashed' Gigabyte Titan Ridge Thunderbolt 3 PCIe card. It reports as having 2 x 20gbs connections. It should be 40gbs, but I believe you need Opencore to get full speed enabled.

I put it in lane 2 (4x) (second from the top), gave it 2x6pin power just in case. Plugged it in to a Sonnet eGPU running a MSI Powercolor RX580. The eGPU was detected no issue in Mojave and was shown in the System Information panel in addition to my Vega 64.

Hot plugging doesn't work, so you have to restart the computer after connecting the eGPU. I had a few minutes spare so I benched it on Geekbench and got 40k-ish for Metal Compute. My natively plugged in (16x lane) Vega 64 was getting 60k+ or so.

I've just installed Catalina and Opencore this evening so I might do some more testing and let you know. I was also thinking of using the TB3 card to offload compute to multiple eGPU boxes (I have 2 x Sonnet eGPUs) since they have their own power supplies and thermal systems. Should be interesting to see how we get on.

 

[Noobraino]

@joevt @universenz

Thanks for taking the time. I’m really interested in your follow up test @universenz

@joevt The external drive i got was borrowed from a friend for testing the card and i just realize it is indeed a 2x HDD Raid 0 so as you stated 360MB/s is most likely ok. I will borrow a Promise Pegasus 4x HDD Raid 0 and test again.