hwmonitor/gpuz etc will report wrong temps and voltages in laptop, my a10-4600m with built in 7660g says it runs at like 120c under full load according to gpuz, im on it right now at it says is at 92c lol
its wrong, 120c would be like 250f, it would be melting if it was that high.
and your overclock might net you 10% at best but at 30fps your only gonna get a merely 3 fps. 30 vs 33 fps, nobody is going to notice that and the extra heat and possible voided warranty is just not worth it.
my 7660g is stock at 650mhz and i had it pegged at 1300mhz once just to see if it would run a benchmark, but i only got like 15% more performance and a whole lot of fan noise and heat, so i just put it back to stock because it didn't make any difference in say, bf3 or skyrim. i could also force the cpu turbo mode if i wanted but i like battery life better so i undervolted my cpu a little and got some cheap low voltage low latency ram and threw in an extra 120gb ssd and i get like 7 hours battery life on my hp m6, same laptop as your dv6 just slightly slimmer.