Do you recommend side-flow or top-flow for full size HTPC?

floepie · Post by **floepie** » Mon Mar 03, 2008 10:23 am

I'm considering a case, which is supplied with one 120mm fan in front and (gasp!) two 60mm fans side by side in the rear, aligned with the CPU. I'm hoping I won't need either of those rear fans, and that a 90 or 120mm CPU fan would suffice.

If that can be accomplished, what would be my best bet - a side-flow fan such as either the Ninja Mini or Zerotherm BTF90 --or-- a top-flow fan such as either the Thermalright XP-120 or SI-128 SE?

If I use the side flow fan, I could aim at the 60mm rear outlets. If I use a top-flow fan, would it be possible to push the upwards through the top vents instead of downward?

I plan to use a cooler Allendale E4500 or E4600 with a 6" high HTPC case :
http://www.thermaltakeusa.com/product/C ... 001bns.asp

jessekopelman · Post by **jessekopelman** » Mon Mar 03, 2008 2:37 pm

If you don't use those rear fans, than top flow is probably better. If you do use those fans, than side flow is probably better. To run top flow in "suck mode" just mount the fan upside down . . .

bonestonne · Post by **bonestonne** » Mon Mar 03, 2008 2:57 pm

you could easily mount the fan to power air upwards and out, but i would say it would be better to use something like the Ninja Mini, and just direct cooling towards the 60mm exhaust areas. also, it would be a wise idea to think about how much dust may enter the system (my system is terrible, i just put off cleaning it once a month or more). filters are a good start, but forgetting (or putting off) cleaning them decreases their effectiveness.

ducting certain intakes to be open, and others to be covered would be something to keep in mind.

jhhoffma · Post by **jhhoffma** » Mon Mar 03, 2008 4:56 pm

I like the top-down for my HTPC only because I can get adequate cooling for the MOSFETs and N/B and the fans can still pull out the hot air collecting at the top of the case.

You could get the same thing out of a tower cooler with a little ducting or something, but it's just easier for me to use a Zalman with a fan swap.

floepie · Post by **floepie** » Mon Mar 03, 2008 7:13 pm

bonestonne wrote:you could easily mount the fan to power air upwards and out, but i would say it would be better to use something like the Ninja Mini, and just direct cooling towards the 60mm exhaust areas.

This is sort of what I was thinking. I think I could get more exhaust from the 60mm fan holes (no fans) than I could by directing air out the top via the slits in the case. If case temps are not low enough, I could spin one of the 60mm fans a bit and leave the other as a gaping hole.

bonestonne wrote:also, it would be a wise idea to think about how much dust may enter the system (my system is terrible, i just put off cleaning it once a month or more). filters are a good start, but forgetting (or putting off) cleaning them decreases their effectiveness.

ducting certain intakes to be open, and others to be covered would be something to keep in mind.

Do you bring up the dust issue b/c I'm considering removing the rear fans from the system, which could allow for more dust entry?

Deiz · Post by **Deiz** » Mon Mar 03, 2008 11:09 pm

Dust is always an issue, to an extent, but it becomes substantially worse when you have negative pressure, because air (and therefore dust) enters through every little gap and crevice in an attempt to equalize the pressure. On the other hand, positive pressure forces air out of those gaps, in an ideal world assuring that dust can only enter from the point of intake.

In reality, your system will not be highly pressurized, because, being an SPCR reader, you're not going to throw a bunch of 150 CFM+ Deltas into the case. At the same decibel level, one 120mm fan should be able to overpower two 60mm fans, so you will likely have slight positive pressure in the case.

Bugsi · Post by **Bugsi** » Tue Mar 04, 2008 10:55 am

I think your plan is sound, with a 120mm pulling air in from the front, with the exhaust area of two 60mm fans in back -without fans- and a large CPU cooler. I agree that a side-flow cooler like a Ninja would be best for keeping the airflow through the case as simple and direct "front to back" as possible, and the airflow in your case will naturally find its way out the exhaust ports in the back. Likewise, if you go with top-down cooler like a Zalman 8700 or Thermalright 120, you'll probably do best with top-venting, and I like the recommendation of using a fan to direct the air out the top. Alternatively you could use ducting to pull air through a side-CPU cooler and duct it out the 60mm exhaust ports.

All that being said, I recently did a build with a 120mm fan pulling air from the front, a Thermalright top-down CPU cooler (92mm fan) and a rear 60mm exhaust port. I put a single quiet 60mm fan on the exhaust. Airflow is nice and quiet.

Schroinx · Post by **Schroinx** » Sun Mar 16, 2008 6:45 am

Bugsi wrote: Alternatively you could use ducting to pull air through a side-CPU cooler and duct it out the 60mm exhaust ports.

All that being said, I recently did a build with a 120mm fan pulling air from the front, a Thermalright top-down CPU cooler (92mm fan) and a rear 60mm exhaust port. I put a single quiet 60mm fan on the exhaust. Airflow is nice and quiet.

I have a dvine 5 case with a similar airflow path, except there is no holes in the top cover. I replaced the 60mm fans in the case and psu with pabst, and thou it is better, it is no good enough. 60mm fans, silence and airflow does not go well together. For anyone who wants to know, play around with the voltage for a 60mm and you'll know what I mean.

I'm about to upgrade my system, and my strategy will be to have a scythe mini with a 80 or 92mm fan blowing at the rear (will remove 60mm fans there) and a duct of some kind to direct the airflow to the holes in the back. That way the warm air from the cpu will not be circulated inside the case and at the same time I can move a lot more air relatively silently with a 80/92 fan compared to two 60mm. Only thing is that I have to find some solution for the 60mm fan in the psu. But that is another story.

Rdgs.
/Schroinx