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mulder

New Member
Joined
Jun 24, 2001
Would putting exhaust fans in the top of my case make any sense? Heat rises so.......
Or would this flurk up the air flow?
 

Phil

Senior Member
Joined
Jan 13, 2001
Location
Bolton, UK
Some people do if you mean on the very top pointing up, though the heat rising issue has little to do with it as pc case fans use forced convection rather than relying on regular convection. so the hot air just moves along the path of the fans. Putting them on top is more a space issue for people who like to load the case up with fans
 
E

Ed

Guest
Um, I get the impression that it *might* make a difference, to change the air flow direction. Some places that got much air might get much less. But of particular concern, a couple of strong exhaust fans might start to suck air into the case through the power supply. I don't know how likely, or what the "fix" would be. (maybe an Enermax (sp?) or Leadman dual fan PSU)
Ed
 

samuknow

Member
Joined
Feb 19, 2001
Location
Indianapolis, IN
I have a 92mm blow hole in the top, 120mm blowing in on my cards, an 80mm in the front blowing in(sheetmetal cut out) and the power supply fan.
There is just enough pos pressure that it stays about 3-4 deg above room temp.
 

merlins_wraith

Member
Joined
Dec 31, 2000
Location
VA
I don't have a particular love for fans (or cutting the case to fit them in). However, when I added two exhaust fans to the top of my HX08 and two fans for intake in the front, my system temp dropped to 1C above ambient temps (the same result I used to get running the case with one side removed). As long as you are supplying the case with intake fan(s) then an exhaust fan should improve your airflow and your temps. Hope this helps!
 

CSaddict

Member
Joined
Jun 19, 2001
Location
CT, USA
It seems the ability to move air in and out in the most unobstructed motion would prove the best plan. If your intake is in the bottom of your case than the top blow hole would make sense. Though in my full tower the top is sectioned off and airflow is constricted so front to back flow works better for me.
 

BrunoPuntzJones

New Member
Joined
Jun 23, 2001
why would you want postive pressure in the case? wouldn't this cause bad air flow and air not to circulate? if you had negative inside (more exhaust, less intake) then the case would always be trying to pull new air in, rather than keep in the hot.
 

Plat

Registered
Joined
Jun 4, 2001
for most cases it doesn't work to well because ur ps lies horizontally over your cpu.

i had a case that had the ps lying vertically so that there was no obstruction between cpu and top of case when case was standing up. the ps would lie next to the cpu (not a lot of clearance w/ a delta sittin on top of the hs tho).

anyway, with this setup a hole in top proved very beneficial. it lowered my cpu temps by 10 - 12 degrees celsius.
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
A lot of tendencies toward eddy currents and dead air spots are overcome by sheer volume. If you have lots of air flowing through the case, they are not a big factor. If you only have a little air, or just enough to prevent major heat issues, yes, you can get dead spots. For a moden PC running a 1G or faster Athlon or Duron, I consider 50cfm or greater as a target for through-case flow.

Hoot
 

cjtune

Member
Joined
Dec 18, 2000
Hoot (Jun 26, 2001 10:30 p.m.):
A lot of tendencies toward eddy currents and dead air spots are overcome by sheer volume. If you have lots of air flowing through the case, they are not a big factor. If you only have a little air, or just enough to prevent major heat issues, yes, you can get dead spots. For a moden PC running a 1G or faster Athlon or Duron, I consider 50cfm or greater as a target for through-case flow.
Hoot

Not really, Hoot, EVEN with high flow rates going thru your casing you can still get stagnant areas. When I migrated my system from a mid-tower to a micro-ATX casing (the stupid mid-tower has only 2 5.25" drive bays), I was lucky I noticed my CPU temp. (only) shot up to 49'C (it has never broke the 44'C limit in a whole year) within 15 minutes of idle (w/o Rain) -and that was with a 80 cfm drive bay twin-fan installed. The problem was that my CPU, in that cramped micro-ATX case, was surrounded by obstacles to air flow, vid. card at the bottom, PSU to the left, cables and memory modules at the front and casing all around. Rectified this issue when I fixed a 80mm fan to blow air thru an opening between the PSU and the vid. card and even half the airflow from that 80mm managed to bring everything down to 43'C (full-load).
 

cjtune

Member
Joined
Dec 18, 2000
Hoot (Jun 26, 2001 10:30 p.m.):
A lot of tendencies toward eddy currents and dead air spots are overcome by sheer volume. If you have lots of air flowing through the case, they are not a big factor. If you only have a little air, or just enough to prevent major heat issues, yes, you can get dead spots. For a moden PC running a 1G or faster Athlon or Duron, I consider 50cfm or greater as a target for through-case flow.
Hoot

Not really, Hoot, EVEN with high flow rates going thru your casing you can still get stagnant areas. When I migrated my system from a mid-tower to a micro-ATX casing (the stupid mid-tower has only 2 5.25" drive bays), I was lucky I noticed my CPU temp. (only) shot up to 49'C (it has never broke the 44'C limit in a whole year) within 15 minutes of idle (w/o Rain) -and that was with a 80 cfm drive bay twin-fan installed. The problem was that my CPU, in that cramped micro-ATX case, was surrounded by obstacles to air flow, vid. card at the bottom, PSU to the left, cables and memory modules at the front and casing all around. Rectified this issue when I fixed a 80mm fan to blow air thru an opening between the PSU and the vid. card and even half the airflow from that 80mm managed to bring everything down to 43'C (full-load).
 

cjtune

Member
Joined
Dec 18, 2000
Hoot (Jun 26, 2001 10:30 p.m.):
A lot of tendencies toward eddy currents and dead air spots are overcome by sheer volume. If you have lots of air flowing through the case, they are not a big factor. If you only have a little air, or just enough to prevent major heat issues, yes, you can get dead spots. For a moden PC running a 1G or faster Athlon or Duron, I consider 50cfm or greater as a target for through-case flow.
Hoot

Not really, Hoot, EVEN with high flow rates going thru your casing you can still get stagnant areas. When I migrated my system from a mid-tower to a micro-ATX casing (the stupid mid-tower has only 2 5.25" drive bays), I was lucky I noticed my CPU temp. (only) shot up to 49'C (it has never broke the 44'C limit in a whole year) within 15 minutes of idle (w/o Rain) -and that was with a 80 cfm drive bay twin-fan installed. The problem was that my CPU, in that cramped micro-ATX case, was surrounded by obstacles to air flow, vid. card at the bottom, PSU to the left, cables and memory modules at the front and casing all around. Rectified this issue when I fixed a 80mm fan to blow air thru an opening between the PSU and the vid. card and even half the airflow from that 80mm managed to bring everything down to 43'C (full-load).
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
Good point cjtune. I was not thinking outside the mid-tower or full-tower footprint. There's that fatal "assume" bug again. ;D

Hoot