Quote:
Originally Posted by Bubba Hotepp 
Look at it this way. When you have grossly mismatched fans what's going to happen? Together they are going to reach an equilibrium with the slower fan spinning faster then it's rating and the faster fan spinning slower. To settle this question once and for all I've sent off a message to a professor of electrical engineering for a definitive answer.
Quote:
Originally Posted by MergatroidÂ
The fan won't burn out. You can put mismatched fans on rads. Put the strongest fan as push, and the weaker fan as pull.
Fans don't get their full cfm when pushing through a rad because the rad will block some of the air flow, and there is a back pressure they have to overcome. So, if you put a weaker fan on as the pull fan, as long as they are not overly mismatched, it will still assist. The fan with the highest static pressure (the delta in this case) should be the push fan. The pull fan doesn't even have to have high static pressure, but a good airflow helps to remove the hot air the push fan is pushing through the rad.
No doubt it's best to match the fans if you can, but I've used mismatched fans myself on an H50 and had no issues at all. Even Corsair George has mentioned same, and he is where I got the information for using the high static pressure fan as the push fan.
I'd have to do those tests myself before I would believe them. Sure, push fans suffer from a backdraft. That's why you need the fan with the best static pressure to be pushing, because it's the best at fighting the back pressure.
Put it this way. If you're just using a push fan on a rad, by itself, it's not going to decrease your performance to add a lower static pressure fan in pull. In fact, the low pressure they create (what there is of it) will be better than the neutral pressure that was there before the fan was added. The CFM of the fan, as long as it's in the same ballpark as the push fan, can only assist in pulling the hot air away from the rad.
I agree with Ceadderman 100% on this issue.
@Ceadderman
Uh, can you explain this please?
"With SP, less is more."
How can less pressure be more? Does less pressure in your kitchen sink faucet push more water or less?
A Corsair stock H100 fan has a static pressure of 7.7mm/H20. That is better than a Corsair H60 fan, which only has a static pressure of 3.2mm/H2O. (both at maximum RPM). Aren't the H60 fans Yate Loons? I think there are different models of Loons as well, and not all of them put out the same pressure.
Please link me to where it says: "Meaning the lower the SP rating the better the performance." because that goes against everything I have ever learned about physics. Higher pressure pushes more air because there is more force (pressure) pushing the air. The best fans can combine high static pressure with high cfm (and likely high noise). Just like more Voltage (electrical pressure) pushes more electrons, more static pressure pushes more air.
The advantage Yate Loons (or AP-15s) have is they have good static pressure at lower RPM, making them a quiet solution for a radiator fan. However, stock H100 fans may outperform the Loons (depending on the model) when both are turned up to full speed because the H100 fans have both a higher static pressure and a higher cfm at full rpm, but are louder. I can only guess as to the actual value of static pressure for the Yate Loons as that number is not actually published anywhere, and we can only go by community testing.
Here is an example:
http://www.overclock.net/t/819736/yate-loon-d12sh-12-round-up-review-56k-no
The best fan in that list is the Sidewinders fan, and it only has a static pressure of 2.99 mm/H20 which is not better than the 3.2mm from the H60 fan, or the 7.7mm of the H100 fans although the performance per noise level would most likely be better on the Loons.
The fan won't burn out. You can put mismatched fans on rads. Put the strongest fan as push, and the weaker fan as pull.
Fans don't get their full cfm when pushing through a rad because the rad will block some of the air flow, and there is a back pressure they have to overcome. So, if you put a weaker fan on as the pull fan, as long as they are not overly mismatched, it will still assist. The fan with the highest static pressure (the delta in this case) should be the push fan. The pull fan doesn't even have to have high static pressure, but a good airflow helps to remove the hot air the push fan is pushing through the rad.
No doubt it's best to match the fans if you can, but I've used mismatched fans myself on an H50 and had no issues at all. Even Corsair George has mentioned same, and he is where I got the information for using the high static pressure fan as the push fan.
I'd have to do those tests myself before I would believe them. Sure, push fans suffer from a backdraft. That's why you need the fan with the best static pressure to be pushing, because it's the best at fighting the back pressure.
Put it this way. If you're just using a push fan on a rad, by itself, it's not going to decrease your performance to add a lower static pressure fan in pull. In fact, the low pressure they create (what there is of it) will be better than the neutral pressure that was there before the fan was added. The CFM of the fan, as long as it's in the same ballpark as the push fan, can only assist in pulling the hot air away from the rad.
I agree with Ceadderman 100% on this issue.
@Ceadderman
Uh, can you explain this please?
"With SP, less is more."
How can less pressure be more? Does less pressure in your kitchen sink faucet push more water or less?
A Corsair stock H100 fan has a static pressure of 7.7mm/H20. That is better than a Corsair H60 fan, which only has a static pressure of 3.2mm/H2O. (both at maximum RPM). Aren't the H60 fans Yate Loons? I think there are different models of Loons as well, and not all of them put out the same pressure.
Please link me to where it says: "Meaning the lower the SP rating the better the performance." because that goes against everything I have ever learned about physics. Higher pressure pushes more air because there is more force (pressure) pushing the air. The best fans can combine high static pressure with high cfm (and likely high noise). Just like more Voltage (electrical pressure) pushes more electrons, more static pressure pushes more air.
The advantage Yate Loons (or AP-15s) have is they have good static pressure at lower RPM, making them a quiet solution for a radiator fan. However, stock H100 fans may outperform the Loons (depending on the model) when both are turned up to full speed because the H100 fans have both a higher static pressure and a higher cfm at full rpm, but are louder. I can only guess as to the actual value of static pressure for the Yate Loons as that number is not actually published anywhere, and we can only go by community testing.
Here is an example:
http://www.overclock.net/t/819736/yate-loon-d12sh-12-round-up-review-56k-no
The best fan in that list is the Sidewinders fan, and it only has a static pressure of 2.99 mm/H20 which is not better than the 3.2mm from the H60 fan, or the 7.7mm of the H100 fans although the performance per noise level would most likely be better on the Loons.
Look at it this way. When you have grossly mismatched fans what's going to happen? Together they are going to reach an equilibrium with the slower fan spinning faster then it's rating and the faster fan spinning slower. To settle this question once and for all I've sent off a message to a professor of electrical engineering for a definitive answer.
And? It may spin faster than it's rating but power usage will remain the same. It certainly wouldn't hurt the fan because it's not limited by a governor the way a Transmission in a car is. I can take an unpowered fan and stack it on a Pusher and it wouldn't do anything but push the other fans blades round. Granted that shouldn't burn out an unpowered fan but it's actually less of a burden on the Pull fan. Not that it would matter much anyway because in Push or Pull the higher speed fan will always drive the speed of the slower one.
~Ceadder
