- Joined
- Mar 22, 2012
- Messages
- 259
- Motherboard
- GA-X99-Gaming 5P
- CPU
- i7-5820K OC @ 4.25 GHz
- Graphics
- Nvidia Titan Xp
- Mac
- Mobile Phone
I don't know if you where looking for a reply to this post as it appears to be a conversation with yourself... lol. There is no reason to use the GenericUSB kext at all considering you only have a Intel USB controller, if your board also had a ASMedia or other USB chip then it may be necessary. Disabling XHCI or using the GenericUSB kext to get speed step is no more than a quirk because of the lack of X99 support from Apple. Although disabling XHCi in bios disables USB 3.0 support in the OS, the 3.0 ports still work at 2.0 speeds so the decision for users is only how important that lost is to them... It's the price you pay for running unsupported hardware.
Left out one detail, I get full 3.0 USB with XHCI disabled in BIOS and installing the generic USB kext. In prior posts this was discussed as either/or, but in my case it's both. When I read the BIOS settings I think the following is true:
1) XHCI disabled, no kext - get speed step, stable system, but no USB 3.0 (I have not tried this combo)
2) XHCI enabled, with kext - get speed step, get USB 3.0, system not stable
3) XHCI disabled, with kext - speed step, get USB3.0, stable system
Gigabyte describes XHCI enabled as a "work around for not having a driver". I am assuming the genericUSB kext adds the XHCI driver so no need to enable XHCI in BIOS. I also have EHCI disabled in BIOS since USB 2.0 driver is native to Yosemite.
My theory is that enabling the XHCI work around in BIOS gives you USB 3.0, but for whatever reason disables speed step in Yosemite. Disabling XHCI work around gives you speed step, then you add the generic kext to get USB 3.0.