too much difference in CFM of intake & exhaust

dust will accumulate faster in ur casing?

example, imagine your case got four (4) fan with the same cfm each of 20 cfm

three (3) exhaust fan | one (1) intake fan

so total intake & exhaust cfm:

• Intake = 20 cfm × 1 fan = 20 cfm
• Exhaust = 20 cfm × 3 fans = 60 cfm

then the exhaust fan got 40 cfm more than the intake fan

so where the hell is the air that the 2 fans gonna suck out from?

from the intake fans? don't think so, the intake air from the intake fan already been suck out by one of the exhaust fan

from the gaps in ur casing --> with no filter can be fitted on to that gap, dust will ride along with it

just my theory though

yup, negative pressure is the best

but for me i don't want the cfm differences between the intake & exhaust fan differs a lot

for my casing:

• i will try to equal the cfm with the intake & exhaust fan
  
• if the case got two (2) or four (4) fan slot --> will make equal
  
• we will always get negative pressure --> remember one more fan, the psu fan
  
• so not much difference in cfm, intake & exhaust fan already equal (in quantity i presume)
  
• want that negative pressure --> got one more exhaust fan, psu fan that is
  
• plus the psu fan ain't that fast (or push high cfm), so not that big difference in cfm anyway
  
• thus less dust will accumulate in time compared to other ppl's casing with hella big difference in intake & exhaust cfm
  

yup, agree with u on this

hot air (from the psu) will be suck by the heatsink's fan to cool off the heatsink

btw, which is more hotter?

1. Hot air from the PSU (like this project), or
2. Hot air from the HDD Bay (like all chassis) --> the air that suck into the case which bypass the HDD bay