Power supply orientation query

[the pokemon kid]

I see a lot of people banging on about positive/ negative case pressure and that the orientation of the power supply is something that is key!

 

But I now have a problem with this comment as power supplies often don't spin up until they are under a large amount of stress. I mean some of these power supplies arent spinning up until they are under 80% + load. Surely this could change people case pressures and effect their cooling performance because of this?

 

[Extingquish]

Nope, since the fan is an exhaust, it would increase static pressure, which isn't a big deal, considering the amount it would affect

[MegaDave91]

If the power supply fan is pulling in fresh air, then it won't have any impact on case airflow. 

[the pokemon kid]

Nope, since the fan is an exhaust, it would increase static pressure, which isn't a big deal, considering the amount it would affect

I mean, because the fan isn't spinning, it means it wouldnt be exhausting anything...

[the pokemon kid]

If the power supply fan is pulling in fresh air, then it won't have any impact on case airflow. 

But what if it isnt spinning, is what I am saying. Could this change a cases airflow from positive to negative because it doesnt spin up unless under extreme loads..?

[Extingquish]

But what if it isnt spinning, is what I am saying. Could this change a cases airflow from positive to negative because it doesnt spin up in most cases?

No, normally the fan is exhausting, so it's reducing the positive pressure, having it not spin would just have it be more positive

[WoodenMarker]

But what if it isnt spinning, is what I am saying. Could this change a cases airflow from positive to negative because it doesnt spin up unless under extreme loads..?

It depends on the scenario. If you are worried, compensate for different psu fan speeds with more or less intake fans. 

In the case that the psu intake is facing the outside of the case, it's airflow is separate from the case's.

[MegaDave91]

But what if it isnt spinning is what I am saying. Does could this change a cases airflow from positive to negative because it doesnt spin up in most cases?

 

It will have its own completely separate airflow. If a case has a filtered intake for the powersupply, you should use it.

[the pokemon kid]

No, normally the fan is exhausting, so it's reducing the positive pressure, having it not spin would just have it be more positive

If it is exhaust or intaking it doesnt matter. It still means it is making some change in the cases air pressure. If the fan then doenst spin up it means that change in air pressure which it would normally make, it is no longer making.

Not all PSU fans spin at all unless they are under high load.

 

 

It depends on the scenario. If you are worried, compensate for different psu fan speeds with more or less intake fans. 

In the case that the psu intake is facing the outside of the case, it's airflow is separate from the case's.

I was more wondering if anyone might known what sort of difference it actually makes. It would be an interesting comparison taking a computer which has a fan less power supply and one which has a fan which spins all the time and seeing the difference in case air pressure because of this...

 

 

It will have its own completely separate airflow. If a case has a filtered intake for the powersupply, you should use it.

Surely if you point it inwards it would make a difference to the computers air pressure.

[Extingquish]

My guess would be that the difference it has on cooling and dust is really negligible

[givingtnt]

Nope, since the fan is an exhaust, it would increase static pressure, which isn't a big deal, considering the amount it would affect

how can you increase static pressur if the fan is an exaust. therefor pulling air out of the case

[Extingquish]

how can you increase static pressur if the fan is an exaust. therefor pulling air out of the case

increased static pressure compared to when the fan is on

[WoodenMarker]

I was more wondering if anyone might known what sort of difference it actually makes. It would be an interesting comparison taking a computer which has a fan less power supply and one which has a fan which spins all the time and seeing the difference in case air pressure because of this...

Not much. 

[ManWithBeard1990]

Just cater for the conditions your pc will be running in most of the time. For most people, that'd be idle, unless you fold. If there's a little more dust buildup over time when the system is under load and has slightly negative relative pressure, that's okay if it won't be doing it all that often.

[SGM]

Not sure if it's been mentioned yet or not but if you mount your power supply with the fan facing down (assuming your case has an intake for it of course!) you essentially isolate it from the air flow (and the heat!) of the rest of the case because it's taking air from the outside, running it over the internal components and then exhausting it out of the back of the unit. 

I know I said facing down, and that's because many case manufacturers put the intake on the bottom but there are some sideways and top orientated designs too.

Anyway, you PSU probably won't have much impact on your air flow (if at all) so I wouldn't worry about it.

[LogicalDrm]

I was more wondering if anyone might known what sort of difference it actually makes. It would be an interesting comparison taking a computer which has a fan less power supply and one which has a fan which spins all the time and seeing the difference in case air pressure because of this...

 

The whole in case airflow and what things have effect and how much is still bit elusive. I have seen couple of good tests but nothing major which would include every variable.

 

Not sure if it's been mentioned yet or not but if you mount your power supply with the fan facing down (assuming your case has an intake for it of course!) you essentially isolate it from the air flow (and the heat!) of the rest of the case because it's taking air from the outside, running it over the internal components and then exhausting it out of the back of the unit. 

 

 

My thoughts excatly. Having PSU pointed down doesn't do anything towards case pressure. PSU casing is pretty tight and air escaping from sides isn't worth taking in consideration. When PSU fan is pointed inside makes it exhausting fan ofc. In that case there's good thing to keep in mind that it uses same air as other air cooled components. Like GPU.

[the pokemon kid]

The whole in case airflow and what things have effect and how much is still bit elusive. I have seen couple of good tests but nothing major which would include every variable.

 

 

My thoughts excatly. Having PSU pointed down doesn't do anything towards case pressure. PSU casing is pretty tight and air escaping from sides isn't worth taking in consideration. When PSU fan is pointed inside makes it exhausting fan ofc. In that case there's good thing to keep in mind that it uses same air as other air cooled components. Like GPU.

 

Some PSU's come as a blower style fan instead of an intake, this could mean that if the cases airflow is negative when it spins that it is pulling unfiltered air into the case. This would in turn mean that it is blowing dust etc directly onto the GPU. If the PSU is orientated towards components internally.

 

It is just something that I was aware of when watching some tech videos. In almost every video of a small form factor case they are taking mentioning the PSU as if the fan is always blowing.

 

 

Not sure if it's been mentioned yet or not but if you mount your power supply with the fan facing down (assuming your case has an intake for it of course!) you essentially isolate it from the air flow (and the heat!) of the rest of the case because it's taking air from the outside, running it over the internal components and then exhausting it out of the back of the unit. 

I know I said facing down, and that's because many case manufacturers put the intake on the bottom but there are some sideways and top orientated designs too.

Anyway, you PSU probably won't have much impact on your air flow (if at all) so I wouldn't worry about it.

 

I dont imagine it would make a huge difference but it would be a difference none the less. It could mean that, that positive filterless computer actually has negative airflow and is pulling in loads of dust...