Re: What's the Helix120 Z-bearing?
We still haven't had time to write a white paper or even a small description about Z-bearing so I am just going to say a few things. It is NOT a ball bearing, so you don't get the usual 5~9V clicking sound you typically get with ball bearing fans. In just a few words the Helix Z-bearing is an improved sleeve bearing. Sleeve bearings rely on the lubrication to reduce bearing friction and temperature. Over time lubricant tends to go away and after some time (typically a couple of years) there is not enough lubrication to keep the bearing cool and maintain a low friction. Z-bearings address this problem with an on-shaft mechanism that basically seals the lubricant inside the bearing. This substantially increases the fan's MTBF.
The motor itself plays a huge part in the actual performance and there is no comparison possible between the 2,200 RPM kukri and the 1,800 RPM Helix. As discussed with Martin and others, the actual noise level and audio spectrum both depend a lot on what the fan is attached to. You will get very different results where you test the fans on the open or if it's attached to low or high FPI radiator, a CPU heat sink, onto the chassis, if there is a fan guard (its shape), if you are using a shroud, etc. The main parameters influencing noise level / audio spectrum being: actual RPM, pressure, volume.
We've actually spent quite a few months selecting and adjusting parts to get to these specifications.. and we will keep doing that because there is always room for improvements
. I pretty much spend half my time in design and half in testing. As much as I enjoy testing in general, I am not afraid to admit that fan testing is subjective and very challenging. Even if you rely on equipment to measure noise level, audio spectrum, flow rates and other static pressure you still have to come up with a testing methodology that will (no matter what!) affect the results (specically: what flow restriction does one apply to the fan). We've obviously thoroughly tested the GT's and I have to admit I am quite pleased with the audio response of the Helix, at least to my ears. I personally never run my fans above 1200 RPM (unless I'm gaming - whenever I have time...
) and that's a speed at which the helix really shines.
I've tested dozens and dozens of fans, and the best advice I can give is: if you are really, really serious about getting fans that fit your ear, then try several of them and be your own judge
StephenEdited by stephenm - 5/17/12 at 4:22pm