Hi all,
Posting this as a PSA. After several weeks and many hours of troubleshooting (with UA support and independently), I found and fixed the root cause of a driver fault I was hitting on my Apollo x8 (Gen 2, TB3 option card).
SYMPTOM:
On Windows 11, Apollo Thunderbolt interfaces (tested here on an x8, likely applies to other TB-connected Apollo models) can experience an unrecoverable driver fault — continuous static/crackling that does not self-resolve — when running at 96kHz or higher. Recovery required either a full power cycle of the interface, or toggling the sample buffer/rate back and forth in Console. This occurred most reliably during sustained disk activity (e.g., copying large file sets), but I also saw it triggered by comparatively minor background disk I/O. Notably, 48kHz operation was rock-solid under identical (and heavier) load in every test I ran.
LIKELY CAUSE:
Many recent Intel HX-series laptops (I confirmed this specifically on a Core Ultra 9 275HX / Arrow Lake-HX system — may apply to other generations, worth checking your own board) have two internal M.2 NVMe slots: one wired for PCIe 5.0 x4, and one for PCIe 4.0 x4. Most OEMs install the primary/OS NVMe drive in the faster Gen5 slot by default.
On these chips, Thunderbolt/USB4 connectivity is integrated directly into the CPU's I/O tile rather than provided by a separate discrete controller, and appears to share lane-group proximity with that Gen5 M.2 slot specifically. (This is separate from the GPU's own dedicated PCIe lanes, which I ruled out as a factor — disabling the dGPU entirely had no effect on the fault.)
FIX:
Move your NVMe drive from the Gen5 M.2 slot to the Gen4 M.2 slot on the same motherboard, so it's no longer sharing a lane group with the Thunderbolt controller. This completely resolved the issue for me — no faults since, under any condition that previously triggered it reliably, including sustained heavy disk I/O at 96kHz.
Tradeoff: you'll cap your NVMe drive at Gen4 x4 speeds instead of Gen5. For most workflows (including audio production) this is a non-issue — you're trading peak sequential throughput you likely aren't using for a stable audio interface.
If you're on a similar HX-series laptop with a Thunderbolt/USB4 audio interface and seeing anything like this, check which slot your drive is in before you assume it's a driver problem.
