{"slug": "generic-pex88048-cards-may-ship-with-misconfigured-eeprom-gen1-x4-upstream", "title": "Generic PEX88048 cards may ship with misconfigured EEPROM (Gen1 x4 upstream)", "summary": "A user reports that a \"henryreal\"-branded Broadcom PEX88048 PCIe switch card bought on Amazon for about $240 shipped with an EEPROM misconfiguration that advertises Gen 1 x4 (2.5GT/s) as its maximum upstream link capability instead of the chip's Gen4 x16, causing zero GPUs to appear on any downstream port. The card enumerates as Broadcom PEX880xx [1000:c012] and its downstream ports also report only 2.5GT/s capability, while a correctly programmed card should show 16GT/s at x16 in LnkCap. The user advises buyers of PEX88048/88096 boards for GPU use to run lspci -vv on the upstream port before building around the card and to return it if LnkCap shows 2.5GT/s, noting there is no user-serviceable fix without Broadcom's proprietary SDK tools.", "body_md": "Due to frustration, claude is responsible for this document.\n\n## \n\nI bought a “henryreal” branded PEX88048 card from Amazon (~$240). It enumerates as a Broadcom PEX880xx [1000:c012], the switch topology appears in `lspci -tv`, fans spin on both R9700s (power through C-Payne device adapters is fine) — but **zero GPUs appear on any downstream port.**\n\nThe root cause is in the upstream port’s capability register:\n\n```\n=== 01:00.0 (upstream port) ===\nLnkCap:  Port #0, Speed 2.5GT/s, Width x4\nLnkSta:  Speed 2.5GT/s, Width x4\nLnkCap2: Supported Link Speeds: 2.5GT/s\n```\n\nThis is a Gen 4 switch chip advertising **Gen 1 x4** as its maximum capability. That’s not a negotiation failure — it’s the EEPROM configuration. The chip can do Gen4 x16, but the board’s EEPROM tells it not to. All downstream ports also show 2.5GT/s capability only.\n\nFor comparison, a working card should show `Speed 16GT/s, Width x16` in LnkCap.\n\n## \n\n```\n# Upstream port\n=== 01:00.0 ===\nLnkCap: Port #0, Speed 2.5GT/s, Width x4, ASPM L1, Exit Latency L1 <32us\nLnkSta: Speed 2.5GT/s, Width x4\n\n# Downstream ports (all empty — no GPUs detected)\n=== 02:00.0 ===\nLnkCap: Port #224, Speed 2.5GT/s, Width x16, ASPM L0s L1\nLnkSta: Speed 2.5GT/s, Width x16\n\n=== 02:04.0 ===\nLnkCap: Port #225, Speed 2.5GT/s, Width x16, ASPM L0s L1\nLnkSta: Speed 2.5GT/s, Width x16\n\n=== 02:0c.0 ===\nLnkCap: Port #227, Speed 2.5GT/s, Width x16, ASPM L0s L1\nLnkSta: Speed 2.5GT/s, Width x16\n\n=== 02:1c.0 ===\nLnkCap: Port #255, Speed 2.5GT/s, Width x16, ASPM L0s L1\nLnkSta: Speed 2.5GT/s, Width x16\n```\n\n## \n\n- \nCard is physically x16 edge connector, fully seated in CPU-direct Slot 1 (X870E Tomahawk, Gen5 capable)\n- \nReseated the card, tried BIOS slot speed at Gen4 and Auto — no change\n- \nNo DIP switches on the board to change upstream config\n- \nGPUs have power (fans spin from C-Payne 6-pin slot power + 12VHPWR from PSU)\n- \n`pci=realloc` in GRUB, Above 4G + ReBAR enabled in BIOS\n- \nVendor website unreachable, no firmware download path\n\n## \n\n**Not all PEX88048 carrier boards ship with correct EEPROM programming.** The Broadcom chip is fine — the board vendor’s firmware is wrong. There’s no user-serviceable fix without Broadcom’s proprietary SDK tools.\n\nIf you’re buying a PEX88048/88096 for GPU use, run `lspci -vv` on the upstream port **before** building anything around it. LnkCap should show 16GT/s (Gen4) and your expected width. If it shows 2.5GT/s, return it.\n\n## \n\n- \nASRock X870E Tomahawk MAX, Ryzen 9 9900X, 96GB DDR5\n- \n2× Radeon AI PRO R9700 (gfx1201) on C-Payne SlimSAS Gen4 device adapters\n- \nUbuntu 24.04.4, kernel 6.17 HWE, ROCm 7.2.3\n- \nGoal: dual-card DDP/FSDP training via RCCL\n\n \n\n \nHi Waylon, I saw your work with the PEX88048 EEPROM configuration. Have you done any work with PEX89000/PEX89144 Gen5 switches? I’m looking at repurposing Dell XE9680 PEX89144 switch boards and would appreciate any advice or issues you think I should watch for.", "url": "https://wpnews.pro/news/generic-pex88048-cards-may-ship-with-misconfigured-eeprom-gen1-x4-upstream", "canonical_source": "https://forum.level1techs.com/t/generic-pex88048-cards-may-ship-with-misconfigured-eeprom-gen1-x4-upstream/251129#post_2", "published_at": "2026-10-02 06:46:22+00:00", "updated_at": "2026-10-02 07:08:19.015608+00:00", "lang": "en", "topics": ["ai-infrastructure"], "entities": ["Broadcom", "PEX88048", "Amazon", "henryreal", "C-Payne", "ASRock X870E Tomahawk MAX", "Radeon AI PRO R9700", "Ubuntu 24.04.4"], "also_reported_by": [], "alternates": {"html": "https://wpnews.pro/news/generic-pex88048-cards-may-ship-with-misconfigured-eeprom-gen1-x4-upstream", "markdown": "https://wpnews.pro/news/generic-pex88048-cards-may-ship-with-misconfigured-eeprom-gen1-x4-upstream.md", "text": "https://wpnews.pro/news/generic-pex88048-cards-may-ship-with-misconfigured-eeprom-gen1-x4-upstream.txt", "jsonld": "https://wpnews.pro/news/generic-pex88048-cards-may-ship-with-misconfigured-eeprom-gen1-x4-upstream.jsonld"}}