The Overclocker attachment is a powerful yet small device, it is a part of the circuits and it allows for (when the special button on it is pressed) the weapon to fire at 200% speeds for up to 5 seconds.
After this 5 seconds (or when the over-clocker is de-activated) however the weapon will stop firing for 0.8x the amount of time the weapon was firing to prevent imminent damage to itself.
Heat resistant weapons and/or weapons with coolants can use this for longer/can cool down faster.
Exclusive to semi-auto weapons. When this is active, any semi-auto weapon becomes fully automatic for the duration!