Mouse disconnects intermittently when running Prime95

[fireblade274]

Hello,
I just started running the program and soon after it starts, while my CPU does come under heavy load the temp is not going over 70, when I was expecting 90+, and my mouse USB port intermittently becomes disconnected and reconnected while Prime95 is running, resulting in a very annoying "binging" sound, and major mouse lag.
Is there something im doing wrong? Short of reducing my clock, can this be fixed? Is this issue common?

My system specs:
Asus z97-a Mobo
i5 4690k oc'd to 4.5, closed loop watercooler
8gb of RAM, 1666mhz
750w powersupply
2x amd 6950's crossfired

My system does nothing like this when doing another (albeit less demanding) stress test, and when playing demanding games at full settings. It has shown zero signs of instability until these issues came up when trying out Prime95

Thank you in advance for any input, much appreciated!