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u/Cubelia

r/homelab r/truenas
Image 1 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 2 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 3 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 4 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 5 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 6 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 7 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 8 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 9 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 10 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 11 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
Image 12 — Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)
▲ 400 r/truenas+1 crossposts

Lekuo B650 on-a-card: Expansions start from here. (Yes, AMD's B650 chipset.)

Ever wondered if AMD chipsets can be repurposed as generic PCIe switch?

No? Well we have an answer.

Expansion is basically on par with what AMD's B650(codename PROM21) offers, just minus some USB ports. Price tag is ~$93USD on Leuko's Tmall store($16 discount if you're Lekuo's bilibili fan).

More can be listed but the post will become a wall of text. I will try answering questions as best as I can since English is not my first language, it's currently working on my X10SDV-4C-TLN2F server with PVE8.4 installed.

You get:

  1. Quad PCIe 4.0 M.2 slots, all x2 if backside ones were populated. x4 if only the front facing ones were populated.
  2. USB-C 20G+10G each, 2x USB-A 10G at rear I/O.
  3. USB PD is available if you plugged in EXT_POWER(PCIe 6P power). EXT_POWER is intended for juicing up power for the entire card if you're maxing out every single port.
  4. 4x SATA 6Gbps ports
  5. Lekuo provided two barebones SSD heatsinks. but due to tight M.2 positions they would not fit when both were populated at the same side.

Observations:

  • Yes, the reliability is not validated as a generic PCIe device. But B650 itself running as motherboard chipset is well covered for quite some time.
  • B650 chipset runs as PCIe root port, that means downstream ports will report running at PCIe 4.0, though still limited by upstream bandwidth. Performance is still fine even under PCIe 3.0.
  • No ACS override patch required. Not only the M.2 slots, you can PCIe passthrough the integrated SATA and USB controllers. Requires motherboard with proper ACS support.(the 2nd chipset on dual chipset AMD motherboards doesn't do ACS so they stay at the same IOMMU group)
  • It's known PROM21 is quite toasty, the temp sensor support on Linux was just submitted some time ago but you can passthrough the USB3.2 controller to a Windows VM and check it via hwinfo.(it can mess with hwinfo detection if you're on an physical AM5 motherboard) It's around 68 deg C on a "meh" vented case.
  • ASPM is supported but I do not have SSDs with functioning ASPM for testing.
  • I know PLX/Broadcom cards exist for cheap but they do not come with integrated SATA and USB controllers, besides having B650 in card form is super cool.

I documented more in my Chinese(zh-tw) post including story behind B650 expansion card(yes there's some backstory):

https://forum.gamer.com.tw/Co.php?bsn=60030&sn=2559036

https://www.ptt.cc/bbs/PC_Shopping/M.1786720009.A.15E.html

Too bad storage prices suck due to AI boom, f**k AI.

u/Cubelia — 5 days ago