So you've got a CECHH PS3 which is already a pretty good ps3 model as it has lower die size on both the cpu and the gpu, the psu doesn't produce that much heat and moreover it has a plastic housing which limits heat transfer between psu and the metal plate over the motherboard, the fan is also a 17 blade and you can't replace it with a 19 blade one because they're different in shape/size.
Thus you can't do that much to prevent ylod because in fact, those models aren't prone to ylod. i'd advise you to simply make it clean (blow all the dust) and replace the thermal paste over the cpu and the gpu with a good one (Arctic MX-2 is a pretty good one, easy to apply, cheap and good quality).
In the extreme case where the fan turns super loud after 1-2 minutes of operating time, it'll be due to the paste under the ihs that gone dry. If that happens, you'll need to open the cpu and rsx IHS and although the RSX one is pretty easy to remove, the CELL one is a pain in the ass, even more on those late fat model ps3. I wouldn't advise you to do this as if it's your first time, you've got more chances to destroy it beyond repair than having better temps.
In conclusion, don't worry that much with your PS3 because it's a good one. Just replace thermal paste and make sure it spreads all over the cpu/gpu surface and you'll be good !
