I think you should overclock your cpu more (or depending on what type of games you play? Is it CPU or GPU intensive?) and if its getting too hot, perhaps get a new heatsink for it as well. I wouldn't buy a new motherboard because it can be a pain in the a** to find something that would be compatible with hardware that might be out of date. If you buy a new motherboard, you might have to replace EVERYTHING including the Memory, CPU, etc.
edit: Overclock now and then wait until you're able to afford more if you still aren't satisfied with the OC. I recommend Intel btw