Hardest component to pick in a massive Home Storage Solution

[JoeComp]

Show me any documentation proving static pressure fans are needed for areas of 2-3 inches of open air? with a vast area of open air on the other side. Static pressure fans should not be needed for gaps that large. (true static pressure fans) Real static pressure fans can have half the airflow. If your saying a hybrid fan would be better suited for that sure.

Nonsense. There is no such thing as "static pressure fans". Some fans are better at moving air when there is a pressure differential across the fan, but it is not a black/white distinction. For a given air-restriction, different fans will have different air throughputs. The actual graphs of throughput as a function of pressure differential (airflow restriction) vary widely among fans. To talk about "static pressure fans" is nonsense. But this is a digression.

The point you are missing is that the HDD sleds have restricted airflow. It is not open air, but rather small cracks and channels that the air has to pass through to get from the intake, past the HDDs, to the backplane. This is analogous to your example of a heatsink. Both have restricted airflow. To create sufficient airflow when there are such restrictions requires a relatively large pressure differential across the fan. Usually, the static pressure that a fan can produce correlates with the airflow that it can pass when there is a large pressure differential across the fan -- larger static pressure tends to indicate that a fan can move more air when it has to fight an air restriction.

As for proof, my HDD temperatures went down more than 5C when I switched the fan wall fans to a model specified with a higher static pressure. This is because the airflow was higher with the new fans, because the old fans could not move as much air with the high pressure differential across them.

diminishing returns here. Disabling 7 W fans is ridiculous unless your running on Solar or paying 50 cents a kilowatt.

The OP was concerned about power dissipation in the fans. I do not think optimizing for power dissipation is "ridiculous". It may be not worth the trouble to some people, but evidently the OP needs to reduce his electricity bill.

If you reduce voltage you will ruin efficiency. voltage is more efficient than currant. Also fans have certain speeds where they are most economical to run. Performance per watt if you want to call it that.

"voltage is more efficient than currant" is complete nonsense, as is "reduce voltage you will ruin efficiency".

With a given case, you need a certain airflow across components to keep them sufficiently cool. The amount of airflow required depends on the ambient temperature and the power dissipation in the components, but assuming those are constant (or taking a worst case), then you need to create a certain air flow through the components and thus through the fans. For a given fan, there will be a certain voltage that will be required in order to obtain that air flow in the case. If that is less than the full rated voltage for the fan, then the power dissipation in the fan will be reduced as compared to operating the fan at full voltage.

 

[SomeGuy133]

Nonsense. There is no such thing as "static pressure fans". Some fans are better at moving air when there is a pressure differential across the fan, but it is not a black/white distinction. For a given air-restriction, different fans will have different air throughputs. The actual graphs of throughput as a function of pressure differential (airflow restriction) vary widely among fans. To talk about "static pressure fans" is nonsense. But this is a digression.

The point you are missing is that the HDD sleds have restricted airflow. It is not open air, but rather small cracks and channels that the air has to pass through to get from the intake, past the HDDs, to the backplane. This is analogous to your example of a heatsink. Both have restricted airflow. To create sufficient airflow when there are such restrictions requires a relatively large pressure differential across the fan. Usually, the static pressure that a fan can produce correlates with the airflow that it can pass when there is a large pressure differential across the fan -- larger static pressure tends to indicate that a fan can move more air when it has to fight an air restriction.

As for proof, my HDD temperatures went down more than 5C when I switched the fan wall fans to a model specified with a higher static pressure. This is because the airflow was higher with the new fans, because the old fans could not move as much air with the high pressure differential across them.




The OP was concerned about power dissipation in the fans. I do not think optimizing for power dissipation is "ridiculous". It may be not worth the trouble to some people, but evidently the OP needs to reduce his electricity bill.



"voltage is more efficient than currant" is complete nonsense, as is "reduce voltage you will ruin efficiency".

With a given case, you need a certain airflow across components to keep them sufficiently cool. The amount of airflow required depends on the ambient temperature and the power dissipation in the components, but assuming those are constant (or taking a worst case), then you need to create a certain air flow through the components and thus through the fans. For a given fan, there will be a certain voltage that will be required in order to obtain that air flow in the case. If that is less than the full rated voltage for the fan, then the power dissipation in the fan will be reduced as compared to operating the fan at full voltage.

Does OP make less than 5 Dollars an hour? If not his time is worth more. Time is money so unless he is making Thailand wages he is wasting more money in time than he is saving. I stand by my point...wasting his energy/time/money.
(On a side note i would not assume to assume people have an understanding that time is money. If the average joe understood that you wouldn't see loads of people doing stupid things like driving 20 miles for a sale or waiting in line or turning their lights on and off multiple times in a day or any number of idiotic things)

If you don't comprehend how voltage and currant work you obviously lack the basic knowledge to even argue this discussion. Not wasting my time on this point. Go read a little more for your own good.

Its also not nonsense that fans have an ideal efficiency. The same goes for motors and fan blades. Again if you can't understand this please go read a little more because you don't have a clue of what your talking about no matter how much you pretend you do.

Again there is a thing called blade design....go read on fan blades and the different types of fans. You clearly need to read more before talking. Certain blade designs create more pressure and others create more flow. Please for the love of anything go read a little more.

Your proof means nothing without referencing the entire specs of the fans. I have done a great deal of research on blade designs and motors and how they work. You clearly fail to provide any meaningful data or actual scientific fact about how they work. You lack a complete understanding of blade design by your first sentence.

 

[JoeComp]

If you don't comprehend how voltage and currant work you obviously lack the basic knowledge to even argue this discussion. Not wasting my time on this point. Go read a little more for your own good.

Hilarious! It is good that you admit that you do not understand basic electronics and will not waste your time posting more nonsense.

 

[SomeGuy133]

Hilarious! It is good that you admit that you do not understand basic electronics and will not waste your time posting more nonsense.

lol joe you get troll post of the day award. Absolutely nothing meaningful posted congrats.

Come back with facts please and not banter.

here is some interesting info on another persons different problem but it gives you some basics on how motors work.
How does voltage and current affect speed and torque of a motor?

How are current and voltage related to torque and speed of a brushless motor?

also that and you could read wikipedia too while your at it.

not this is only DC brushed motors. There are brushless and several other kinds of motors. They each react differently to current and voltage and also have different ideal RPMs for efficiency.

Additionally, there is also the blade design. IIRC correctly various blades have optimal outputs at certain speeds. They don't always scale linearly. Its been a while since i read up on blade design and how all the various kinds function. You can gather a little knowledge by reading the spec sheets of fans. Here is one of mine

1500 RPM 72cfm 21 rpm per cfm 3 watts 2.5 mm-h20
2500 RPM 115cfm 22 rpm per cfm 7.2 watts 6.7 mm-h20
3500 RPM 154cfm 23 rpm per cfm 15 watts 11.1 mm-h20

only current is being changed. If you mess with voltage you will increase heat waste and lower efficiency per the other articles.

Also notice pressure grows exponentially vs CFM but fairly linear with wattage. This is a bearing type fan BTW.

Brushless motors work very differently. Brushless motors are more efficient in high RPM uses. So scaling for a brushless motor looks very different.

but hey lets just banter and not provide anything meaningful.

You are advising the OP with out even understanding the design or specs of the fan so again no one listen to this guy. Not a clue of what he is talking about.

Using a JBOD chassis:
I don't have MOBO+CPU+RAM=~150 Watts idling, that's like >$20 per month that I don't have to pay for. Certainly makes JBODs more attractive than a server case with disks.

no PC should ideal at 150 W....hell many don't even use that under load. A PC ideal should be 20-50 watts tops. Only PCs that ideal at 150W are heavily OCed performance rigs like my server/NAS. It ideals are 150 but thats because i haven't finished tweaking the 1650v3,, which ideals at 40-60 watts which is stupid. I have to play with voltages and off sets more and fix the idealing. It ideals at 1.375v and not 1.3v which is like 20 watts or so.

 

[JoeComp]

only current is being changed. If you mess with voltage you will increase heat waste and lower efficiency per the other articles.

Again, this is nonsense. If you change the current sourced through a fan, the voltage across the fan also changes.

As for motor efficiency, that is a red herring. As I already explained, the key point is that the fan wall needs some minimum air flow to keep the HDDs cool, and given that constraint, how can the fan power consumption be reduced? The answer is to lower the voltage to the fan (which also lowers the current, of course). While this may reduce the motor efficiency, that is irrelevant as long as the fan power consumption is reduced (which it definitely will be if you lower the voltage) while maintaining at least the required air flow to keep the HDDs cool.

 

[kandrey89]

lol joe you get troll post of the day award. Absolutely nothing meaningful posted congrats.

no PC should ideal at 150 W....hell many don't even use that under load. A PC ideal should be 20-50 watts tops. Only PCs that ideal at 150W are heavily OCed performance rigs like my server/NAS. It ideals are 150 but thats because i haven't finished tweaking the 1650v3,, which ideals at 40-60 watts which is stupid. I have to play with voltages and off sets more and fix the idealing. It ideals at 1.375v and not 1.3v which is like 20 watts or so.

I have a storage server, 6 WD enterprise disks, 3 noctua fans, supermicro mobo, xeon processor, 16GB of ram and when idling, yes it does draw 200W I've measured. Server is 3-4 years old, sounds like a lot, but it's Haswell 1st or 2nd generation I think. Assuming 6W per HDD, rounding up that's ~150W for the rest of the computer.

 

[SomeGuy133]

I have a storage server, 6 WD enterprise disks, 3 noctua fans, supermicro mobo, xeon processor, 16GB of ram and when idling, yes it does draw 200W I've measured. Server is 3-4 years old, sounds like a lot, but it's Haswell 1st or 2nd generation I think. Assuming 6W per HDD, rounding up that's ~150W for the rest of the computer.

You can see my specs below and I only hit 150-200W because my xeon doesn't drop voltage and i have high powered fans with 13 or so drives. Something is wrong with your system. I should be using less than 150 but thats because i have mine maxed out for performance and cooling.

I'll double check later but i never remember mine running over 200 idle even with ridiculous fans and a CPU that won't sleep or drop voltage with twice the amount of drives.

Again, this is nonsense. If you change the current sourced through a fan, the voltage across the fan also changes.

As for motor efficiency, that is a red herring. As I already explained, the key point is that the fan wall needs some minimum air flow to keep the HDDs cool, and given that constraint, how can the fan power consumption be reduced? The answer is to lower the voltage to the fan (which also lowers the current, of course). While this may reduce the motor efficiency, that is irrelevant as long as the fan power consumption is reduced (which it definitely will be if you lower the voltage) while maintaining at least the required air flow to keep the HDDs cool.

say nonsense all you want your still wrong and i pointed that out countless times. Anyways I am done I posted actual facts so I don't care anymore. Any reader here can tell your full of shit and have nothing valuable to say.

 

[JoeComp]

say nonsense all you want your still wrong and i pointed that out countless times.

No, I am not wrong. This is basic electronics. For a component to be able to change the current without changing the voltage, it would need to have an I-V curve with a completely vertical line. The only common passive components that approximate this are diodes (rectifiers), but fans (electric motors) do not behave like diodes. The I-V curve for a fan (DC motor) is upward sloping and nearly straight -- much like a resistor. When the current sourced through a fan is varied, the voltage across the fan varies accordingly.