optimum add-on cards for 2-slot systems (Talos II Lite and Blackbird)

[pocock]

I've had some discussions with other developers about the POWER9 platform and one observation I've made is that people are looking at a choice between Talos II Lite or Blackbird.  Many don't need a dual CPU system and can't afford the full Talos II.

To iron out bugs in software, it is really vital to have a critical mass of developers using the platform and I suspect most of them are going to use either Talos II Lite or Blackbird.  When they narrow their choice down to those products, the next thing that comes to mind is: what should they put in the PCIe slots to get best use out of their workstation?

The wiki contains a large list of compatible products but what I'm really thinking about here is making a shortlist of five to ten really interesting products and putting them on the comparison page

Here is a summary of the problem:
 

• most people will want to put a GPU in the x16 slot - some GPUs, like the Radeon Pro W5700 throw in a USB-C socket or some other bonus which is really useful on a system like this with limited expansion slots
• with the x8 slot, most people will probably want a card that can give them some combination of SSDs (U.2 NVMe), legacy SATA disks and hopefully some other ports like OCuLink or ethernet on the same board as a bonus.  Can anybody comment on which boards are optimal in this scenario?

Some other permutations come to mind: for example, people who don't do a lot of graphics may be happy with a GPU in the x8 slot and use the x16 slot for OCuLink.  Hopefully we will also see some external OCuLink GPUs in the future but none seem to be available right now.

Feel free to add comments here or at the bottom of this wiki page

[bobpaul]

I'm trying to figure out the best way to handle my Talos II lite. I got it with a single slot NVME card and an old Radeon graphics card.

So here's what I'm thinking right now:

• m.2 to SATA card with using a SATA controller chip, such as this using the ASM1166 chip
• x8 or x4 PCIe card with a PCIe switch chip that has 2-4 NVME slots such as this card using the ASM2824 PCIe3 chip (or maybe a cheaper one using PEX 8724 chip)

I haven't yet pulled the trigger. My concern is that the NVME to SATA adapter + sata cables will be too tall and I won't be able to plug anything into the x16 slot right below it. 

So maybe instead of the NVME-SATA adapter, perhaps an NVME to PCIE riser is better. I could flip a standard PCIe SATA controller upside down and plug it into the riser using one of the backplane connectors in front of an unpopulated PCIe slot.

With 2 of the NVME-riser adapters maybe I could put a SATA adapter, sound card, dual nvme, and a decent graphics card in  the Talos II lite.


I really hope this gets better on the Power10 products. Only 2 PCIe slots (neither supporting burfaction) on the Talos II lite and Blackbird does present a big challenge. The Blackbird at least has onboard audio and SATA.

Alternating the ports on the Talos II standard also would have been nice. Then on the Talos II Lite we could have had a gap between the x8 and the x16 slots rather than having both cards right next to each other and lots of deadspace at the bottom of the board.

On the Talos II standard is that all of the PCIe x16 slots are next to another slot. It's extremely common for graphics cards to cover 2 slots. It would be nice if the bottom slot was an x16 slot instead of an x8 slot and if those board-edge connectors were moved somewhere else. Then one could install a 2-slot x16 graphics card without losing any connectors. Right now one either loses access to an x8 slot or an x16 slot if they install a big graphics cards.

[Borley]

Having an on board nvme header is pretty much the norm these days. If any new boards yet to be announced have one integrated, that would be one less major hurdle for builders to overcome.