PSU strange air flow; please advise

[Navid]

I have an FSP350-60PN power supply.
http://www.home2000.net/client/fspgroupusacom/proddetail.asp?linenumber=77#

I noticed that it exhausts some air inside the case!
You can see the holes if you open the drawings (or click on this PDF link)
http://www.home2000.net/client/fspgroupusacom/images/FSP350-60PN_D.pdf.

The picture to the right shows the side that faces the back of the case and
sends warm air out. The picture in the middle is the side that is inside
the case and sucks air in the supply from the case. You can see the fan in
that picture (this fan sucks air in instead of pushing air out). The
picture to the left is also inside the case and has some small holes on it.
This is the side I am concerned about. I opened the case and held a small
piece of paper near the holes. Sure enough, air was coming into the case
from those holes. Why are those holes there? I have blocked them by a
tape.

I think all of the air that the supply sucks from the case should be sent
out of the case. None of it should be sent back into the case. Am I
missing something?

Thanks,

Navid

 

[Vic.]

I have an FSP350-60PN power supply.
http://www.home2000.net/client/fspgroupusacom/proddetail.asp?linenumber=77#

I noticed that it exhausts some air inside the case!
You can see the holes if you open the drawings (or click on this PDF link)
http://www.home2000.net/client/fspgroupusacom/images/FSP350-60PN_D.pdf.

The picture to the right shows the side that faces the back of the case and
sends warm air out. The picture in the middle is the side that is inside
the case and sucks air in the supply from the case. You can see the fan in
that picture (this fan sucks air in instead of pushing air out). The
picture to the left is also inside the case and has some small holes on it.
This is the side I am concerned about. I opened the case and held a small
piece of paper near the holes. Sure enough, air was coming into the case
from those holes. Why are those holes there? I have blocked them by a
tape.

Bad idea, IMHO. See below.

I think all of the air that the supply sucks from the case should be sent
out of the case. None of it should be sent back into the case. Am I
missing something?

I would guess that without these four slots, there would be a dead
spot (wrt air flow) in the top front of the PSU case. By "front", I
mean the side of the PSU that is nearest the front of the pc, when
installed normally.

It's likely that the four small slots were introduced to purposely
allow air to leak out, so there's airflow in the region I described.
This flow, although slight, could be enough to stop the temperature
within this section of the case rising too high (whatever "too high"
is).

Nice idea to have a slow, quiet, large fan to cool the PSU, but in my
view the execution, in this PSU design , is flawed - I prefer it if my
PSU doesn't push heat into the case.

Might not be a deal-breaker for you - I don't know if the airflow or
its temperature is significant - but you've spent the bucks, so it's
for you to decide if the additional heat is acceptable.

Lose that tape though!

Vic.

 

[Navid]

Bad idea, IMHO. See below.


I would guess that without these four slots, there would be a dead
spot (wrt air flow) in the top front of the PSU case. By "front", I
mean the side of the PSU that is nearest the front of the pc, when
installed normally.

It's likely that the four small slots were introduced to purposely
allow air to leak out, so there's airflow in the region I described.
This flow, although slight, could be enough to stop the temperature
within this section of the case rising too high (whatever "too high"
is).

Nice idea to have a slow, quiet, large fan to cool the PSU, but in my
view the execution, in this PSU design , is flawed - I prefer it if my
PSU doesn't push heat into the case.

Might not be a deal-breaker for you - I don't know if the airflow or
its temperature is significant - but you've spent the bucks, so it's
for you to decide if the additional heat is acceptable.

Lose that tape though!

Vic.

Vic,

The fan sucks air from the case into the PSU. This increases the air
pressure inside the PSU with respect to the outside. So, air moves out of
the PSU from its back. Air is not pushed inside the case.

Thanks for your reply.

Navid

 

[Vic.]

The fan sucks air from the case into the PSU. This increases the air
pressure inside the PSU with respect to the outside. So, air moves out of
the PSU from its back. Air is not pushed inside the case.

Thanks for your reply.

Navid

I'm puzzled by this reply.

To quote your origonal post: "I noticed that it [the PSU] exhausts
some air inside the case!".

How can you now say that "Air is not pushed inside the case"???

Please clarify!

Best,

Vic.

 

[Navid]

The fan sucks air from the case into the PSU. This increases the air
pressure inside the PSU with respect to the outside. So, air moves out of
the PSU from its back. Air is not pushed inside the case.

Thanks for your reply.

Navid

I'm puzzled by this reply.

To quote your origonal post: "I noticed that it [the PSU] exhausts
some air inside the case!".

How can you now say that "Air is not pushed inside the case"???

Please clarify!

Best,

Vic.

I am sorry about my confusing messages.

There are a lot of holes on the back of the PSU where it sends air out of
the case. A lot of air flows that way.
There are a few tiny holes on the side that is inside the case. From those
tiny holes, a little bit of air is exhausted inside the case. But, this
flow is negligible compared to the main air flow that sucks air from the
case and exhausts it out the back.

In my original post, I was asking if anybody knew why these few small holes
existed on the side inside the case.

Regards,

Navid

 

[larrymoencurly]

I've seen PSUs where slots like that were placed next to a big
resistor or choke or a transistor tucked away in a jungle of
components, but I've never seen that in cheapo PSUs, where details
like that seemed to be ignored. In two instances, a resistor ran very
close to its maximum power rating for still air, so any fan air flow
probably helped a lot. OTOH some other PSUs had resistors that had
turned dark from running hot.