2×RTX 3090 + EPYC box running qwen3.8-flash-next at ~38 tok/s

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What I have: - CPU: EPYC 7551 (32c/64T, Zen 1) - Board: Supermicro H11SSL-i (SP3), Rev 2.0 - RAM: 128 GB DDR4-2133 (all 8 channels full) - GPU: 2x RTX 3090 (48 GB total, PCIe 3.0) - 1500 W PSU What I run: - Qwen3-Flash-Next (177B total / ~6B active MoE, IQ4_XS) on Ilama.cpp. Experts live in system RAM, hot ones cached in VRAM. Single stream = 38 tok/s. Two parallel requests drop to ~4 tok/s each. Budget: ~$800. Realistically that's either one more RTX 3090 or a CPU upgrade (a Zen 2 "Rome" EPYC d