SA260324R-0146
① SA Source
- Source: 開啟完整 SA 文章
- Section:
LPX Compute Tray - Line hint:
181
Context Before
The LPU modules are mounted in a belly-to-belly on the PCB, meaning 8 LP30 modules on the top side of the PCB and the other 8 LP30 modules on the bottom. All of the connectivity that comes out of the LPU are via PCB traces and given the dense all-to-all mesh for intra-node connections this requires a very high spec PCB to support the routing.
Evidence
The belly-to-belly mounting is used to reduce PCB trace lengths across the ‘X’ and ‘Y’ dimensions.
Context After
Something interesting about the system is the important role the FPGAs play. Nvidia refers to the FPGAs as “Fabric Expansion Logic” which serves multiple purposes. First, they act as a NIC which converts the LPU’s C2C protocol into Ethernet to connect to the Spectrum-X based ethernet scale-out fabric. It is this scale-out fabric through which the LPUs connect to GPUs in the decode system.
② Atomic Claim
belly-to-belly mounting 用來縮短 PCB 在 X 與 Y 維度上的 trace length。
- Epistemic Mode:
ASSERTED - Mapping Status:
COMPLETE
③ Semantic Frame
{
"attribute": "TRACE_LENGTH_REDUCTION",
"context_nodes": [],
"entity": {
"id": "04_knowledge_base/PCB",
"label": "PCB"
},
"frame_type": "ATTRIBUTE",
"qualifiers": {
"condition_text": null,
"numeric_mentions": [],
"temporal_mentions": []
},
"value": {
"numeric_mentions": [],
"value_text": "belly-to-belly mounting 用來縮短 X 與 Y 維度上的 PCB trace length。"
}
}④ Canonical Entity Mapping
| Role | Surface Label | Canonical Target |
|---|---|---|
| entity | PCB | PCB |
⑤ Human Review
請在 Properties 逐項確認：
- 原文 → Atomic Claim 是否忠實
- Atomic Claim → Semantic Frame 是否忠實
- Canonical Entity mapping 是否正確
- Epistemic mode 是否保留原文語氣
- 最後選擇
review_action
Review state
Markdown 內文不是正式 approval。只有 Apply bridge 寫入的 Decision Ledger event 才是正式決策。