should I replace the stock fans

[poggwea]

Ultra m925

120mm

Lots of case fans on sale. Should I replace the stock ones? Also can you tell me how many fans I can put in here and where. I want max airflow. I know two in front 1 rear and 1 200mm on side but is there one on bottom or top. Any places for fans there?

[Arc_Jester]

I wouldn't recommend that case as it doesn't look like a good quality full-tower.

[OnekillWalter]

dont forget, more fan, more airflow, more noise as well!! 

[multifrag]

Not sure if its worth replacing. Most fans will work the same, apart from higher class ones. If you want to add more fans it is your choice but by adding more it will just add more noise. Look at your temperatures and if they are fines it would not make sense to  upgrade.

[MDBT]

Only 2 reasons to replace case fans IMO; need more flow or need less noise.  Probably won't know the answer to either until you get the case and put the components in.  The cheaper fans that come in these kinds of cases are usually loud and inefficient but if you add one or two extra you have lying around you can usually get enough airflow out of it to keep the temps under control.  That just leaves the noise issue to contemplate.

[Arc_Jester]

It can hold 2x 120mm in the top and 1x 120mm in the bottom along with what you mentioned. You don't need to replace the stock fans unless they're loud or can't create suitable airflow.