Lowering FSB Increases WPA2 Speed

When i lower my FSB i get more kh/s ( From 160 kh/s to 262 kh/s ) In WPA2

has anyone herd of this and is this a real speed increase?

This only happens when i lower FSB using ASROCK OC Tuner and not from windows BIOS.

My max speed with my GPU before was only 160 kh/s (WPA2)

The lowest stable FSB i can achive withought windows crashing is 215

motherboard G41M-VS3 ASROCK
W8.1
R9 280X OC
Hashcat v1.31.64 (Windows)