Major Issues with all USB3 ports on my Hackintosh. Lil' help, please?

Hi all. I'm having major issues with my USB3 ports. On a powered hub ( worse without ). The only external drive working more or less ok is a 2.5" SSD, I'm guessing that's because of its low power needs. All other do connect for a while, but have very limited performance speed, then crash the system. Every single time. Any idea what to do, please? I have tried the generic USB3 kext, have taken it off again, and so on... many thanks for reading this, if you have any ideas, please do let me know, I'm about to give up on this thing ( although everything else is working fine ). Toby / model identifiers etc. all below.

--- anything really dumb and obvious I'm doing wrong??? Wouldn't surprise me in the least...:-)

Multibeast 7.4.1

Machine in question:

System Version: OS X 10.10.5 (14F2511) Kernel Version: Darwin 14.5.0 Boot Volume: OSX Boot Mode: Normal

Model Name: Mac Pro Model Identifier: MacPro3,1 Processor Name: Quad-Core Intel Xeon Processor Speed: 3.07 GHz Number of Processors: 1 Total Number of Cores: 4 L2 Cache (per Core): 256 KB L3 Cache: 8 MB Memory: 24 GB Processor Interconnect Speed: 6.4 GT/s Boot ROM Version: MultiBeast.tonymacx86.com SMC Version (system): 1.30f3 Serial Number (system): G8805OTX5J4 Serial Number (processor tray): SOMESRLNMBR Hardware UUID: A33473A7-61C5-5311-9F6D-71D56C110F24

USB Ports:

USB 3.0 Hi-Speed Bus:

Host Controller Location: Built-in USB Host Controller Driver: GenericUSBXHCI PCI Device ID: 0x0194 PCI Revision ID: 0x0003 PCI Vendor ID: 0x1033 Bus Number: 0x01

USB2.0 Hub:

Product ID: 0x2813 Vendor ID: 0x2109 (VIA Labs, Inc.) Version: 90.11 Speed: Up to 480 Mb/sec Manufacturer: VIA Labs, Inc. Location ID: 0x02100000 / 1 Current Available (mA): 500 Current Required (mA): 0

USB2.0 Hub:

Product ID: 0x2813 Vendor ID: 0x2109 (VIA Labs, Inc.) Version: 90.11 Speed: Up to 480 Mb/sec Manufacturer: VIA Labs, Inc. Location ID: 0x02110000 / 3 Current Available (mA): 500 Current Required (mA): 0

Flash Card Reader/Writer:

Product ID: 0x6366 Vendor ID: 0x058f (Alcor Micro, Corp.) Version: 1.00 Serial Number: 058F63666438 Speed: Up to 480 Mb/sec Manufacturer: Generic Location ID: 0x02113000 / 6 Current Available (mA): 500 Current Required (mA): 100