Even overclocked, the G3258 cannot really match up to the 4150 as it's a dual-core without Hyper-Threading. It will also perform poorly in multi-threaded applications. Even then, getting a Z97 board and an aftermarket cooler will not be worth it. Dollar for dollar, a cooler will cost ~25 pounds and a Z97 board would be ~20 pounds more than an H97 board. That's already half the CPU's price. I would expect a 50% performance increase from that, since I'm spending half the CPU's price on overclocking stuff, but you only get a 10% performance increase.