Baffles in a PC power supply

Bill_Bright · Wednesday at 5:19 PM

Bobaganoosh said:
It is partially blocked.

Technically speaking, yes, you can say it is blocked.

But then - not really.

For argument sake, lets say that baffle thingy is 1/3rd (33%) the width of the fan opening.

Is 1/3 of the air flow being stopped (blocked)? No.

Yeah, again, technically speaking, a little bit of back-pressure is being developed, slightly limiting the maximum CFM capacity. But by 33%? No. The vast majority of that flow simply turns the corner.

Now "IF" there was a duct on the other 2/3, there would be more "blockage" because the air would be compressed, creating friction and slowing it down. But there isn't any ductwork. It is essentially wide open spaces imposing no restricting pressures at all.

dirtyferret · Wednesday at 5:28 PM

Shrek said:
why are they blocking part of the fan, and then 'could this be done better'.

We have gone over why they do it several times. Could it be done better? Sure but is the cost associated with "better" worth the better performance.

Here you go @Shrek, I'm going to help you sleep at night. These guys build power supplies for critical systems (think health sector) so the stakes are a little higher.

Some power supplies are designed to be force-cooled using a system fan, which removes the excess heat from the enclosure. In these cases, the airflow required for adequate cooling will be specified in the power supply data sheet. It is important to bear in mind that this is the airflow needed at the location of the power supply itself — a fan placed even a short distance away will not be sufficient.

Since air always follows the path of least resistance, only a portion of the air pushed by the fan will reach the power supply where it is needed. Internal panels for directing airflow (baffles) will help channel air along the required path to reach and cool the target components.

Bobaganoosh · Wednesday at 5:37 PM

@Bill_Bright agreed. I was saying technically it is slightly blocked, but the pros outweigh whatever cons here.

Also, @Shrek no on the slats, not just because there's no room, but because the point of this isn't to point air in one spot. It's to force a directionality of air movement in the box when the fan is perpendicular to the direction of the box they're trying to force the air to flow in and prevent eddies and pockets of uncirculated air. This could also be accomplished with ducting (or a different type of fan), but there's not enough room for that.

SL2 · Wednesday at 5:44 PM

To stop the air from exiting direclty through the exhaust, without passing the components.

Shrek · Wednesday at 5:46 PM

dirtyferret said:
Here you go @Shrek, I'm going to help you sleep at night. These guys build power supplies for critical systems (think health sector) so the stakes are a little higher.

Some power supplies are designed to be force-cooled using a system fan, which removes the excess heat from the enclosure. In these cases, the airflow required for adequate cooling will be specified in the power supply data sheet. It is important to bear in mind that this is the airflow needed at the location of the power supply itself — a fan placed even a short distance away will not be sufficient.

Since air always follows the path of least resistance, only a portion of the air pushed by the fan will reach the power supply where it is needed. Internal panels for directing airflow (baffles) will help channel air along the required path to reach and cool the target components.

Greatly appreciated; I will indeed sleep more soundly tonight.

dirtyferret · Wednesday at 5:48 PM

Shrek said:
Greatly appreciated; I will indeed sleep more soundly tonight.

my wife says it's a gift, when i talk about PC parts to her she falls asleep instantly too

Shrek · Wednesday at 5:52 PM

For another day/thread

@TimatPSUTest.com

we all know that the electrolytic capacitors are a weak point for switched mode power supplies, so are there any inductor-based designs for regulating the output voltage?

natr0n · Wednesday at 6:01 PM

It can make a lower spec fan within parameters as well.

Steevo · Wednesday at 6:07 PM

Yeas ago Dell built a slot A machine that used 1 fan, just one. It pulled air over the CPU through a duct, through the fan and exhausted it out the power supply.

Dell Optiplex 9010 9020 AIO All In One Power Suppy Fan Duct Shroud Vent 2SQ0R01 | eBay

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natr0n · Wednesday at 6:24 PM

Steevo said:
Yeas ago Dell built a slot A machine that used 1 fan, just one. It pulled air over the CPU through a duct, through the fan and exhausted it out the power supply.

Dell Optiplex 9010 9020 AIO All In One Power Suppy Fan Duct Shroud Vent 2SQ0R01 | eBay

Item For Sale Is An Excellent Condition Genuine Dell Optiplex 9010 9020 AIO All In One Power Suppy Fan Air Duct Shroud Vent Plastic Cover. Fan Duct is in Excellent Working Condition.

www.ebay.com

Ive torn down many dells and some have 120mm thick as a brick fan in front, like a vacuum to pull air.I think it pulled air over cpu cooler as well with fins touching the clouds. I have random bits of dell parts still.

Calenhad · Wednesday at 6:31 PM

Steevo said:
Yeas ago Dell built a slot A machine that used 1 fan, just one. It pulled air over the CPU through a duct, through the fan and exhausted it out the power supply.

Dell Optiplex 9010 9020 AIO All In One Power Suppy Fan Duct Shroud Vent 2SQ0R01 | eBay

Item For Sale Is An Excellent Condition Genuine Dell Optiplex 9010 9020 AIO All In One Power Suppy Fan Air Duct Shroud Vent Plastic Cover. Fan Duct is in Excellent Working Condition.

www.ebay.com

Fan ducts in prebuilds were pretty common 20-ish years ago. I don't recall the last time I saw one. But I'd say around 2010

Bobaganoosh · Wednesday at 7:17 PM

Dell has some of the best ducting in PC cases I've ever seen (mostly because it isn't done much). They will do some of the craziest molded duct parts just so they can run one obnoxiously loud fan for the whole chassis (which is also an old box chassis with molded plastic parts around it). Yup, as natr0n said, one "thick as a brick" fan. I have wondered over the years how much money was saved, if any, going with less fans and instead spending all that effort on ducting. Seemed more like a company motto or archaic internal design rule than having any logic to it lol.
Some examples:

wheresmycar · Wednesday at 7:30 PM

#22 said:
Assume that PSU engineers know better than you E.g. lack of directing the airflow resulting in need of fan spinning faster.

dirtyferret said:
On the flip side it "can" direct cooler air to key components to lower temps and prolong component life. My guess is the fan & PSU have test evidence of that otherwise why bring in additional part & labor costs but I doubt they will share those tests results.

*It actually increases airflow in the PSU therefore making it more efficient.

well the baffle is no longer baffling... didn't know its purpose. Oddly/ignorantly, i too thought it was a guard of some sort.

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