CONSTANT usb problems - Asus P8 Z77-V LX

so I have this ongoing issue with my usb 3 hdd's disconnecting or crashes my system when writing data to them,it will get half way through then bottom out. I have been into policies and enable write catching and better performance I have also been into device manager and unchecked the save power option on all hubs under power management, and still the problem exists! doesn't seem to matter what port they are plugged into either... i read somewhere about bios settings?? but to be honest this stuff is a bit beyond me... ive provided details of the bios setting, if anyone can help you would be more than appreciated as this is costing me time ,money and a lot of stress. Thanks

bios setting:
INTEL USB2.0 EHCI CONTROLLER - ENABLED
LEGACY USB SUPPORT - ENABLED
LEGACY USB3.0 SUPPORT - ENABLED
INTEL xHCI MODE - SMART AUTO
EHCI HAND-OFF - DISABLED

Have responded in your other thread in storage section.

Mark