H and B series boards allow only multiplier and to some extent voltage tweaking, on select models like Pentium G3258, which has now been expanded to other K-SKU models. That is fine for minor OCing on low wattage models but I wouldn't try putting an i7 or even i5 for OCing on these. Most of the H and B series boards don't support XMP RAM which can, to a large extent, make things worse.
So if OCing is the priority, invest in Z series.
So if OCing is the priority, invest in Z series.