@jorge
Have you done the usual optimations in bios ?
Disabling any and all power saving and turbo boost, and clocking all cores the same. A 5960 I would clock at 3ghz on all cores to start somewhere and increase the clock if the temp allows it.
Setting memory timing to what the manufacturer recommends for the memory sticks, auto setting in bios sometimes get it wrong.
Also.
Updating any and all drivers, even non-audio related devices can have a disastrous influence if they cause interrupts.
LatencyMon is a good tool to find any problematic, programs and drivers.
Most of this can be Googled, if you need more information.