What do you mean cabinet? If you want more cooling you generally replace the case but that is not an operation for a novice. Sometimes you can remove the fans that are already present in your case and replace them with a higher quality fan, you may also have a few places inside your case that can obviously accept a fan but there isn't one there now so you could add one. There are lots of forums out there for HP owners try posting questions in one of those as I'm sure other owners have upgraded the cooling for their machines. Your motherboard may have unused "fan headers" on it, usually these are white and have a plastic sort of socket around them. Fans can be two or three pin depending upon if your motherboard can monitor the fan speed and if the fan has the sensors for same, usually both two or three pin fans will work you just won't have the fan speed monitor if you plug a two pin fan in a three pin plug or a three pin fan in a two pin plug. Filters are really pretty useless just accept that you will be opening your case every few months and using the shop vac to suck out the dust, you could also use blow mode on a shop vac but be very careful if you do that as some shop vacs can produce quite a hurricane and you could damage something or disconnect something accidentally. Just a good old fifteen dollar box fan can also help a lot if you just aim it at your computer case, of course that is probably a bit noisy but having a lot of fans in your case can get loud too!