I'm sure of that, 8400GS is slower than 7300GT, and G3258's iGPU wiped its butthole with 7300GT when I compared those.
Hell, even Final Fantasy VI felt kinda choppy with 7300GT even OC'd to the max, but I've even played BF4 (720p, everything on low) with the iGPU OC'd
e: I'm running my G3258 @ 4.6GHz with ~1.47 volts, the CPU is delidded, Coollaboratory Liquid Ultra between the die and IHS, and Thermalright Macho Direct as the cooler. Never seen temps go over 75C, and fan spins ~300rpm on desktop, max ~700rpm under heavy load... kinda inaudible..