G3258 Build Cooler option..

A good air cooler will get you over 4.0GHz, or just about any water cooler for beyond that. The better the water setup, the further you can go. Something of decent quality with a 120mm radiator should get you in the 4.4GHz range, with 4.8GHz or so with great 240mm+ setups (though the investment here, if doing it for just this chip, is not worth the return).
 
The stock cooler should be fine up to about 4GHz - depends on whether you get a good chip or not.
You can overclock with a H81 motherboard.
Suggest you keep the Vcore voltage to 1.2V

Spending more money to get another 10% performance out of a G3258 at 4.4Ghz is not worth it
 
Best budget cooler on the market.

2w6vz38.jpg

Image from: techpowerup.com


PCPartPicker part list / Price breakdown by merchant

CPU Cooler: CRYORIG H7 49.0 CFM CPU Cooler ($34.50 @ Newegg)
Total: $34.50
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-11-16 20:04 EST-0500

http://www.hitechlegion.com/reviews/cooling/heatsinks/42980-cryorig-h7-universal-cpu-cooler-review?showall=&start=3
Review from hitechlegion ^


[video="https://www.youtube.com/watch?v=kNF-GHQthro"][/video]
Simple installation video here ^

Unmatched Compatibility
Zero RAM Interference


Focusing on providing the widest range of
compatibility, the H7 utilizes an asymmetric slanted
heatpipe layout to move the heatsink away from the
RAM zone, Offering optimal compatibility for RAM
with tall heat spreaders on both Intel 115X and
AMD platforms.


n3r821.jpg

Image from: proclockers.com




 


Don't completely disagree with this, unless you can get a good O/C with the stock cooler. It's probably as good on this chip as something like the 212 evo. The 3258 even at 4.4(which is what mine runs at) only runs at about 50tdp. Unless you really have to crank the voltage.......
I think the 3258 is a good chip to learn on, tinker with, and cause general computing mayhem, but a fast I3 will beat it in anything but single threaded app, assuming you can get a decent Over/Clock.