Dual MI50 rig spews gibberish

Classic mixed-GPU pain: this looks less like a bad model and more like a brittle inference stack tripping over legacy AMD cards, Vulkan fallback, and device enumeration.

• –Mixing a 7900 XT with dual MI50s can expose backend assumptions about GPU order, memory layout, and supported kernels.
• –Infinite garbage tokens usually smell like a broken runtime path, bad backend compilation, or driver mismatch rather than a model spontaneously failing.
• –An 850W PSU is probably too tight for three hungry AMD cards under load, so power instability could be making an already fragile setup worse.
• –The quickest debug path is to test each MI50 alone, then the two MI50s without the 7900 XT, and only then reintroduce the third GPU or fix ROCm properly.
• –Vulkan can be a useful escape hatch, but for older Vega20-era cards it often behaves like “it boots” is not the same as “it is actually stable.”