Changing board just to attain better OC is a waste of money.

You're better off changing that processor to a Core i3.

Nothing about fancy but rather the chipset affects your mileage with it.

H81 and B85 you're limited to BCLK overclocking.

Z97 board is where you get to unleash the full potential of it.

G3258 @ 4.5Ghz is only as goods as i3 4130 only for single-threaded performance.

When you judge the processor overall the G3258 is far from the Core i3.

Put into factor that in order to reach 4.5Ghz you'll have to pump vcore and even stock cooler doesn't handle it that well, so you'll have to spend on aftermarket cooler.

In the end when you compare, i3-4130 is still faster (HT helps heaps) while runs cooler and draws less power.

Back to your question - yes, you have to change board to get better OC.

As mentioned H81 / B85 is limited.

Yup, depends on luck and what you're running.

I got mine to 4.6Ghz I think but not totally stable.

It depends on what you want, some people run Prime95 for stability test but for me I just use games and whatever I do that is processor intensive, if it passes then it passes.

Gigabyte GA-Z97X-Gaming 3