Cooling fans - How to read the specs

[Lambofreak]

For the TL;DR version skip to the bold items.

Hi all, I was on here about a year ago about my build that I was going to do, went ahead with pretty much everything in that list and it worked out great! So happy with the computer, I've never known speed like it and blows any game away I throw at it (1080p anyway)

Anyway, now that its been done for a while I keep looking at new hardware etc and I've noticed the sexiest thing I've ever seen: http://www.pccasegear.com/index.php?main_page=product_info&cPath=25_961&products_id=28528
Which of course I have to have.

At the moment though I have a white and blue theme so to go with the new case I need new fans for a black and red theme - red fans. I've been doing a bit of research and what I'm wondering is how do I understand the tables they put up? What I assume is that more airflow (CFM) is better, especially when balanced with a low sound level (dBA). Is this correct? How does static pressure (mm/H20) factor into it?

Then how does this translate to real-world performance? Does more airflow and lower sound level actually translate to lower temperatures and quieter operations?

For instance I wanted to buy these because they look siiiiiiiiiick but the specs aren't nearly as good as something say like this, but I just wanted to check my understanding of how they're rated basically.

I've searched on the forum and on the internet for any articles but can't really find what I'm after. So any help would be greatly appreciated.

 

[Someone Somewhere]

More static pressure means they can shove air through thicker heatsinks. More airflow means they shove more air. Reasonably closely related, and higher is better.

Low sound level is generally good.

The Corsair fan, while quieter and higher throughput, is much lower pressure. Good for general ventilation, but don't hook it up straight to your CPU heatsink or a radiator.

 

[Paperdoc]

Your first reply from Someone ... covered most of it. The Corsair is ideal for case ventilation. If you used it as a CPU cooler pushing air through a heatsink, it would not produce the CFM specified. All fans push less air against a higher backpressure (see the graph on the Thermaltake page). In this case, the Thermaltake is designed to deliver its specified flow at twice the backpressure that the Corsair unit is designed for, so the Thermaltake is better suited to CPU cooling.

I note also that the Thermaltake has a LED ring on it, whereas the Corsair's colored ring is just colored plastic trim.

NOTE that both of these fans are of the 3-pin type, not 4-pin. As a general rule, look very closely at the mobo port you plan to plug the fan into. You should match the fan type to the port type so that the mobo can control fan speed properly. If you don't, here's what will happen: a 3-pin fan connected to a 4-pin mobo port cannot have its speed controlled - it will always run at full speed. The exception to that is this: SOME mobos allow you to set a fan port's mode in BIOS Setup, so that you can tell a 4-pin port to behave like a true 3-pin port. A few are even smart enough to figure this out for themselves and make the adjustment for you. Most of the time, though, such flexibility is on the CPU_FAN port, but not on the SYS_FAN ports used for case ventilation fans.

These fans come with low-noise adapters that you can optionally connect into the fan's power leads. These are intended for use only if you plug them into a fixed 12 VDC power source like a Molex output connector from the PSU. They thus allow you to reduce the fan's speed (and hence less noise and less cooling) if you feel you don't need max cooling. Note, for example, on the Thermaltake's page that the lower noise figure (when using a "low-noise adapter") is accomplished by reducing its speed from 1400 to 1000 rpm. However, if you connect the fan to a mobo port and let the mobo control the fan's speed automatically, do NOT use those adapters - they interfere with the automatic control and may cause fan malfunction.

 

[Lambofreak]

Thanks guys so much for your answers, that makes so much sense. So basically if say for instance if I wanted to select fans to just push exhaust air out the top of the case I would choose fans with a high CFM but not necessarily a high static pressure. But then if I had future plans of maybe installing a water cooling system and wanted to re-use my current fans to keep the look consistent then I would have to balance high airflow with high static pressure?

As for actual real-world selection it seems like Noctura fans perform well across the board but god they're ugly... I really really love the look of the Thermaltake Riing and from what you guys have said I'm guessing they would be well suited to a radiator etc, problem is though I've haven't read many positive things about the Thermaltake fans in terms of quality? I think I may just stick with what I know and put the red version of what I already have in there.

And I'll do a little bit more research in regards to the fan connectors.

 

[Paperdoc]

Noctua fans are very good; I'm happy with the ones I have. In fact, if you examine their website, you will find that the sell both fans designed for maximum air flow at low backpressure, and fans designed for higher backpressures. They and others have several fan lines for different purposes, sizes, pin configurations, etc.

 

[Lambofreak]

Noctua fans are very good; I'm happy with the ones I have. In fact, if you examine their website, you will find that the sell both fans designed for maximum air flow at low backpressure, and fans designed for higher backpressures. They and others have several fan lines for different purposes, sizes, pin configurations, etc.

Yeah from the specs they seem great, but only thing is they look like dog poop IMO. If they at least come in colour options different from poo brown I'd be all over that.

So Thermaltake = bad? (in terms of quality)