I wanted to ask if using faster memory would benefit an Intel IGPU. I know it does give a good boost to APU integrated graphics but what would be the fps boost(if any) when going from say 1333 to 1866 or 1660mhz memory on an Intel HD4000 or HD3000 IGPU?
Yes it should but I would expect much lesser performance increase due to a higher clocked RAM as compared to an APU. The reason is intel IGP will primarily bottleneck due to its lower core performance, not due to memory performance.
It should but it's kind of sad if anyone is gaming on that. I have HD3000 in my laptop along with a 555m and if I forget to turn the 555m back on (it uses lots of power and I have a switch that completely deactivates it) my games lag so much (you can tell as soon as you're on the launch screen and your mouse can't even move fluidly). I have 8 GB of DDR3 1600 memory.