I have 4 * 120mm system fans on my case 2 blowing in + 2 blowing out. one of the ones that is blowing in is giving me noise lately and i ordered one to replace it with. can i take it off while i wait for the new one to arrive. that would be 1 blowing in and 2 blowing out. there is also the 120 mm of the psu blowing in too.
More aboutsystem cooling
Yeah, you'll be fine. Temps MIGHT raise a couple degrees, but nothing dangerous.
Should be good but the PSU should not be venting into the case. Newer should be pulling air in from bottom and out the back, older top mount should be pulling from in the case out the back.