Well, if you ask me, I think overclocking by .7 Ghz is kind of a bad idea, even though AMDs CPUs are known to take more temps but O.C risks a lot of things, you need an aftermarket cooler if you plan to overclock and most likely a better power supply, Links to your specs would help me tremedously, I use http://newegg.com/ to review items, also about that bottleneck, yes, every Machine has one to a certain extent, but if you plan to up the RAM to 8GB and upgrade to the top of the Radeon HD 6000 series, then mostly likely. Your CPU and the amount of RAM you have now are most likely going to slow down your GPU a little bit, and less likely the RAM.