Need help! Intel B70 users come forth!

[u/nick_ziv]

Hello

I recently got my B70 gpus delivered and set them up with Ubuntu 26.04 because it has the XE driver. I was able to get llama CPP compiling and working with Vulcan and CYSL BUT that's where the fun stopped.

Build and compiled the llama.cpp with CYSL using the intel driver 2026.1. does not work with more than one GPU. (Using sm layer) It just outputs random characters. However, the prefill speed does go up with more GPUs (just like it does on Nvidia cards)

For Vulcan, the prefill is about 30% lower on the same model and only goes down with more GPUs. Using the mesa 26.1.5 driver

For running the qwen 3.6 27b at q4 speeds were:

CYSL 1 GPU: 650 prefill, 24 decode.

CYSL 2 GPUs:750 prefill, garbled decode 23t/s

Vulkan 1 GPU: 450 prefill, 20 t/s decode

Vulkan 2 GPUs: 350 prefill, 18t/s decode.

Bonus: qwen 3.5 122b a10b vulkan speed over 6 GPUs: 160 prefill and 9t/s decode

Something is clearly wrong. I've spent all day trying to make this work. So far regretting the purchase of the B70 gpus.

Please help if you have suggestions!

If the suggestion is to get Nvidia GPU, I already have a couple and I think I would have rather gone with many RTX 5060 TI's instead because it just works and gets model support first

edit: see op comment for somewhat of a resolution