I was using
MSI Afterburner back in the days, when my Asus G73Jw was still working. GPU Tweak was and is still too buggy.
How much you can do, depends on the notebook you own, the enabled bios options it has as @chrsplmr mentioned and what hardware you have and how good the cooling is.
Maybe some further informations from your side could help to give a better answer to your question.
Desktop: Xigmatek Elysium | Rampage IV Extreme | i7-3960X | G.Skill 32Gb DDR3 2133Mhz|fastest Asus MarsII on the planet:cool: core 950Mhz| Kingston HyperX SSD 240Gb + 300Gb Intel 300series SSD + Velociraptor 600Gb + 3TB HDD | Enermax Maxrevo 1500W| 3xDell U2412m |
Laptop: Samsung 940X3G | i7-4500U | 8Gb RAM | 256Gb SSD | 13.3" 3200x1800 |