I was also looking at some OC website, those VCCSA and VCCIO voltages aren't too low?
VCCSA should be 0.925v (CPU default). You don't need to raise that unless you are going to try BCLK overclocking.
VCCIO should be set at 1.05v (CPU default), as the increase isn't likely to affect the overclock at that low a speed.
CPU PLL at 1.9v may be required, but leave it at the default setting and see if it works first.
For me, none of those settings needed to be increased for me to get my 2500K to 4.8GHz.
I would do steps 1-5, then skip straight to step 9. If that turns out to not be stable, then change the CPU PLL. The other voltages listed shouldn't need to be changed at all.