One of the most critical components for a multi-GPU build is often overlooked: PCIe riser cables. Here's what you need to know to avoid performance bottlenecks.
The Problem with Cheap Risers
USB-Style Risers: Don't Do It
Cheap mining risers with USB-style connectors only provide x1 bandwidth (~4 GB/s). For LLM inference, you need full x16 bandwidth (32 GB/s).
What You Need
- LINKUP Ultra PCIe 4.0 x16 Risers
- 30-50cm length for optimal signal integrity
- Individual lane shielding for Gen4 stability
Performance Impact
| Riser Type | Bandwidth | Performance Loss |
|---|---|---|
| USB mining riser | 4 GB/s | Severe |
| Generic x16 riser | 16 GB/s (Gen3) | Moderate |
| LINKUP Ultra x16 | 32 GB/s (Gen4) | None measurable |
Recommendation
Invest in quality riser cables. They're a critical component that you don't want to skimp on.