On my GA-770T-USB3 motherboard, adding exactly SUSPEND_MODULES="xhci-hcd" to the exact file /etc/pm/config.d/unload_module works extremely well for me on Maverick with kernel 2.6.35-25-generic.
On my GA-770T-USB3 motherboard, adding exactly SUSPEND_ MODULES= "xhci-hcd" to the exact file /etc/pm/ config. d/unload_ module works extremely well for me on Maverick with kernel 2.6.35-25-generic.