Coming to manual overclocking, I was not able to add much to the GPU core. My best result came with +70MHz to the GPU, +600MHz to the memory with power and temperature sliders at their maximum levels. I also ran the fans at 100% while trying to achieve a maximum overclock.
While running Fire Strike, this overclock resulted in a real-world frequency of 2038MHz. The fans, running at full pelt, were actually able providing enough cooling that this frequency held stable for 5 runs of Fire Strike stress test, and that is definitely a testament to the proficiency of MSI's cooling solution.
In contrast, left in OC mode, the Gaming X Trio's core frequency would stabilise at around 1961MHz after 5 runs of the same stress test.
This overclock does bring some performance increase as you can see above.
Personally, I'm not sure the extra noise from having the fans at 100% is worth it, as the card is hardly slow in the first place. If you want to squeeze every last frame out of the card, though, you will notice some gains from manually overclocking.