Sparkle Arc Pro B60: only 150 GB/s VRAM bandwidth (spec 456)

A Sparkle Arc Pro B60 owner reports the card delivering only 150 GB/s of VRAM bandwidth in clpeak's --global-memory-bandwidth test, against a 456 GB/s specification, and is asking other B60 owners to run the same test to confirm. The owner says dense LLMs run at roughly half the speed of other reports, with Qwen3-27B Q4_K_M reaching 8.6 t/s versus 16 t/s on other B60s using the same llama.cpp build and flags. The discrepancy matters because if the 150 GB/s figure is reproducible, the card's memory bandwidth is about a third of its rated spec and would explain the slower token generation.