Cpu coolers and side vents?

Well, I've never messed with aftermarket cpu coolers, but I've been
looking at them recently and it seems that there are two varieties --
the ones that blow across and the ones that blow down on the cpu.
Currently the "across" style seems to be ahead in the ratings -- but
to me the "blow down" scheme seems to make more sense for a tower case
with a side vent. Does anyone here have a case with a side vent which
couples directly up with the cpu cooler?

Davej wrote:
Well, I've never messed with aftermarket cpu coolers, but I've been
looking at them recently and it seems that there are two varieties --
the ones that blow across and the ones that blow down on the cpu.
Currently the "across" style seems to be ahead in the ratings -- but
to me the "blow down" scheme seems to make more sense for a tower case
with a side vent. Does anyone here have a case with a side vent which
couples directly up with the cpu cooler?

I have a coolermaster case which is designed to have a shroud to direct
the cpu hotair out the side of the case (or coolair into the cpu fan),
but my case didn't include the shroud. I wrote CM about it, but they
never answered.

Here's the case open showing the shroud http://snipr.com/q7yc1 You
can't see the mobo/cpu location as the case is empty.

Here's the case closed showing the shroud's perforated side port
http://snipr.com/q802t

If you had a cpu fan directed down on/ toward/ the cpu, then coolair
would be coming into it from outside the case; if you had a cpu fan
directed away from the cpu, then cpuair would be going outside the case
via the shroud and sidepanel perforations.

--
Mike Easter

Davej wrote:
Well, I've never messed with aftermarket cpu coolers, but I've been
looking at them recently and it seems that there are two varieties --
the ones that blow across and the ones that blow down on the cpu.
Currently the "across" style seems to be ahead in the ratings -- but
to me the "blow down" scheme seems to make more sense for a tower case
with a side vent. Does anyone here have a case with a side vent which
couples directly up with the cpu cooler?

Cooling in a computer, happens in two stages.

Hot objects inside the computer, transfer their heat into
the computer case air.

The computer case exhaust fan, move the hot case air
out of the case. It is replaced by fresh cool air,
coming through intake vents.

The style of CPU cooler, can influence in some way,
the movement of the hot air. I had one aftermarket CPU
cooler, that had a "cloud" of warm air around the
CPU socket. I needed a stronger exhaust fan, plus opening
some vents on the front of the computer case, to
dissipate that "cloud".

When a computer involves multiple cooling fans, sometimes
the fans are working against one another. The simplest and
most unambiguous case, is when you have one exhaust fan.
Now, consider the power of that fan, and the fan in the
power supply. It is possible for your single exhaust fan,
to cause air movement backwards through the power supply.
I'm only mentioning that possibility, to indicate that
figuring out what is going to happen, is pretty complicated.
So when someone tells me they "have seven fans and it still
runs hot", then I have to ask whether those fans are working
against one another. Maybe only one of the fans has a good
net airflow, and all the other ones do is make a noise.

Generally, you want a front to back airflow on an ATX case.
The idea there, is the hard drives get the coolest of the
airflow. Other components in the computer, can take a bit
more heat. But once you add additional fans, then unexpected
things can happen.

I used the "kleenex" test on a lower intake fan on one of my
cases, and found air was blowing through that fan backwards!
So the hard drive next to that fan, was actually getting warm
air from inside the case. That happened, because another intake
fan was about twice as powerful, and completely overpowered
the other fan. The "kleenex" test should have cause the kleenex
to get sucked into the fan intake. But instead, it was blown away from
the case. I thought it was pretty funny at the time.
Changing to an exhaust only setup, gave me a better front
to back cooling result.

When the CPU cooler blows towards the back of the
computer case, that might make it easier to encourage
a front to back airflow. If the CPU cooler blows down
onto the motherboard, then the rear exhaust fan will be doing
most all of the work. But blowing down, can also provide a bit
of cooling for adjacent heatpipe coolers. On some motherboards, the
heatpipes for chipset or MOSFETs, get a bit warm, and then
downward cooling may help them. If the chipset were to
get really hot, eventually it would become unstable (65C+ perhaps).

You can stick a finger on some of the components inside your
computer case, to determine how well they're currently
cooled. (Like your chipset cooler - mine is ice cold, because
I have a crappy chipset :-) RAM bandwidth only 3GB/sec.)

In the case of hard drives, you can use SMART to read out the
hard drive temperature. For example, using HDTune 2.55, my two drives
are at 33C and 32C. The room temperature is pretty warm right
now, so in fact they aren't that much warmer than the room air.
If your hard drives are a lot hotter than that, you may want
to adjust how things work a bit. My drives are right next to
the only fan on this particular case, so they don't have much
choice but to be at room temperature. (My current computer case
is an antique, with no exhaust fan. I fitted a large intake
fan externally, on the front of the computer, and it
works just fine. That even helps the air move through the power
supply in the right direction. But you can also get your fingers
snipped, if you stick them in the fan... No fan guard.)

Doing a good job is more complicated than it looks. You may
end up trying a couple different setups, until you get
something you're happy with, a balance between cooling
and quietness.

I've never used the side vent on any of my cases. On one,
I fitted an aluminum plate, to block it off, because I wanted
a strict front to back airflow.

Paul

On Aug 16, 2:24 pm, "Mike Easter" wrote:
[...]
I have a coolermaster case which is designed to have a shroud to direct
the cpu hotair out the side of the case (or coolair into the cpu fan),
but my case didn't include the shroud. I wrote CM about it, but they
never answered.

Here's the case open showing the shroudhttp://snipr.com/q7yc1 You
can't see the mobo/cpu location as the case is empty.

Yes, that is just what I was thinking of. I'm going to try to do that.

On Aug 16, 5:41 pm, Paul wrote:
[...]
So when someone tells me they "have seven fans and it still
runs hot", then I have to ask whether those fans are working
against one another. Maybe only one of the fans has a good
net airflow, and all the other ones do is make a noise.

I used the "kleenex" test on a lower intake fan on one of my
cases, and found air was blowing through that fan backwards!

Well, I agree with that. Sounds like a good check.

Generally, you want a front to back airflow on an ATX case.
The idea there, is the hard drives get the coolest of the
airflow. Other components in the computer, can take a bit
more heat. But once you add additional fans, then unexpected
things can happen.

Yes, but just to confuse things my ATX power supply pulls air in the
back rather than exhausting it out the back. I understand that was the
ATX standard. I may open the supply up and reverse that fan. I like
the idea of room temperature air blowing on the cpu from a dedicated
side vent and I also like the front intake blowing air on the HD's.
The problem with rear exhaust is that so much of the back of the case
is restricted by the card slot area. Maybe mesh card slot fillers are
available?

In the case of hard drives, you can use SMART to read out the
hard drive temperature. For example, using HDTune 2.55, my two drives
are at 33C and 32C.

I may try that. Thanks.

Davej wrote:
On Aug 16, 5:41 pm, Paul wrote:
[...]
So when someone tells me they "have seven fans and it still
runs hot", then I have to ask whether those fans are working
against one another. Maybe only one of the fans has a good
net airflow, and all the other ones do is make a noise.

I used the "kleenex" test on a lower intake fan on one of my
cases, and found air was blowing through that fan backwards!

Well, I agree with that. Sounds like a good check.

Generally, you want a front to back airflow on an ATX case.
The idea there, is the hard drives get the coolest of the
airflow. Other components in the computer, can take a bit
more heat. But once you add additional fans, then unexpected
things can happen.

Yes, but just to confuse things my ATX power supply pulls air in the
back rather than exhausting it out the back. I understand that was the
ATX standard.

New one on me. I've lost count of the amount of PC's I've built and ATX
PSU's I've fitted and I've never come across a standard ATX PSU that sucks
air in from the back.

--
SteveH

"Davej" wrote in message
...
On Aug 16, 2:24 pm, "Mike Easter" wrote:
[...]
I have a coolermaster case which is designed to have a shroud to direct
the cpu hotair out the side of the case (or coolair into the cpu fan),
but my case didn't include the shroud. I wrote CM about it, but they
never answered.

Here's the case open showing the shroudhttp://snipr.com/q7yc1 You
can't see the mobo/cpu location as the case is empty.

Yes, that is just what I was thinking of. I'm going to try to do that.

I got that on a new computer I just bought and I had it on the old one that
just blew up Power supply took out almost everything.

You can, and I am, going to put a 3" fan in there (between the case and the
shroud, so it sucks air into the case and into the chip fan. I never had a
problem with that and I like the set-up.

Thanks,
Bob