I have set RSX clocks like this:
Underclocked for XMB mode (350/400)
Overclocked for games (700/850)
FAN profile to manual (30% XMB +10% while gaming)
It works very well but sometimes, when i open any game (loaded ISO from XMB PlayStation 3™ folder) both RSX clocks and FAN speed don't change at all, no matter how much time i wait, it works back only after closing and reopening the game.
Sorry if it's a known issue, i read over open issues but didn't find any mention to this.