That sounds like about how my overclocking went with a G3258 with my GA-H81M-DS2V v1.0 board when I got it. It had BIOS F5 out of the box, which supported G3258 overclocking.
I tried just increasing the multi, was able to boot Win7 64-bit at 38x, blue-screen at 39x, and no POST at 40x. But running DC load on it, I had to downclock to 36x, otherwise it would crash.
When Gigabyte released the F6 BIOS for my board, to fix Win10 issues, I found that now, I could magically overclock higher. I could also increase the vcore beyond 1.200V.
I was able to boot Win7 64-bit at 42x, but it wasn't 100% stable running DC load, even boosting the vcore from 1.200V to 1.300V. So I had to settle for 40x at 1.200V, which is where I'm at now.
So check for a BIOS update, it might improve overclocking.
Edit: Oh, there was something else I discovered, with the newer F6 BIOS. Setting XMP, would prevent me from being able to overclock as high, for some reason.