Care and feeding of Scythe low-pressure (SlipStream) fans

Post by **MikeC** » Fri Nov 16, 2007 8:51 am

FYI, I've been in communication w/Scythe. Looks like they'll send us samples of their entire new design fan inventory.

But then, of course, we'll be under the gun to produce the reviews... Better take another look at our fan test system; it underwent another massive restructure after the last roundup, and I really haven't had any time to appraise it fully.

Sooty · Post by **Sooty** » Fri Nov 16, 2007 9:37 am

Mike, I hope you have plans to test these too: Sharkoon Silent Eagle 1000 and Noctua NF-P12.

Post by **MikeC** » Fri Nov 16, 2007 9:54 am

Sooty wrote:Mike, I hope you have plans to test these too: Sharkoon Silent Eagle 1000 and Noctua NF-P12.

Sharkoon has ibeen unrespnosive -- even a referral from another hardware site didn't work. I think their attitude is they don't sell in the US or Canada; ergo, a web site in Canada can't do them any good PR.... pretty shortsighted, imo -- half our audience in the EU.

As for Noctua, I'll find out whether we have any of those...

Post by **NeilBlanchard** » Fri Nov 16, 2007 10:08 am

Hello,

I will check on the undervolting sometime tomorrow. OTOH, the 500RPM Slip Stream really doesn't need to be undervolted...

Cerb · Post by **Cerb** » Fri Nov 16, 2007 11:49 am

NeilBlanchard wrote:Hello,

I will check on the undervolting sometime tomorrow. OTOH, the 500RPM Slip Stream really doesn't need to be undervolted...

No, but 500 RPM might not hold the temps down during the Summer. In that case, being able to go up would be nice.

Post by **NeilBlanchard** » Fri Nov 16, 2007 8:24 pm

Hello,

The 800RPM Scythe Slip Stream (SSS?) starts fine a 5v -- and it is very slightly slower/quieter/less air than the SSS 500RPM at 12v. It blows more air at 12v than a GlobalWin NCB does at 5v; though it is also a bit noisier, too. (The GW NCB has the lousy "parallel" struts, btw...and it makes a much lower pitch noise than the SSS.)

At 5v, the 800RPM SSS and the 1300RPM GW NCB are blowing a very similar amount of air, and the SSS is slightly quieter. The GW NCB sound is dominated by the low pitch blade/strut noise (kind of a constant "purring"), while the only noticeable sounds from the SSS is some very soft bearing "ticks" -- probably when I move it. Each has the whoosh of air flow, of course. Since the GW NCB is too loud at 12v anyway, the SSS is the quieter fan and more useful fan from 5-12v.

The 500RPM SSS won't start at 5v, nor will it start at 7v. But again, it is so quiet at 12v, and frankly is probably only useful at 12v. At 5v (after bump starting it) it barely turns. At 7v the air flow is pretty feeble, though maybe as an intake fan blowing over an HD -- it is so quiet at 12v though, it really only makes sense to use it this way?

Felger Carbon · Post by **Felger Carbon** » Fri Nov 16, 2007 9:02 pm

NeilBlanchard wrote:The 500RPM SSS won't start at 5v, nor will it start at 7v.

Neil, I posted that the 500 "started by the skin of its teeth" at 7.7V, IIRC. I discovered later that I was wrong. The SSS has a new, different, and superior starting circuit. Its behaviour threw me off track. That fan will start at 7V, but just barely (and this time I mean barely). This is remarkable behaviour for such a low-RPM fan.

It is doubtless a bad idea to assume that all samples of the 500SSS will start at 7V. So your caution is well taken. But a 500SSS may start at 7V. Honest.

An SSS fan, close to its starting limit but above that limit does this: first it weakly trys to start, but fails. Very short pause. A very energetic alternate circuit takes over and accelerates the fan blades. Once turning is established, control is returned to the normal fan motor circuit.

jaganath · Post by **jaganath** » Sat Nov 17, 2007 2:32 am

An SSS fan, close to its starting limit but above that limit does this: first it weakly trys to start, but fails. Very short pause. A very energetic alternate circuit takes over and accelerates the fan blades. Once turning is established, control is returned to the normal fan motor circuit.

Those clever Scythe engineers!

do you think they have copied your kick-start circuit design FC?

Post by **NeilBlanchard** » Sat Nov 17, 2007 3:43 am

Greetings,

My problem is the FSG "Green" PSU doesn't "like" to run a single fan at 7v. It won't unless I have another fan running at 5v...

Felger Carbon · Post by **Felger Carbon** » Sat Nov 17, 2007 3:44 am

jaganath wrote:...do you think they have copied your kick-start circuit design FC?

Nope. The fan guys have finally awakened to the (now old) economics of integrated circuits: transistor complexity costs nothing. What costs money are the wire bonding pads on the silicon die, the bonding wires themselves, and the package. The number of transistors does not affect the price at all.

You can buy CPUs these days for well under a hundred dollars that have hundreds of millions of transistors. A million transistors is what, 25 or 50 cents? So 20K to 40K transistors cost a penny! Not even the newest fan controllers come anywhere near that "one cent" complexity!

Cerb · Post by **Cerb** » Sat Nov 17, 2007 2:42 pm

NeilBlanchard wrote:Hello,

The 800RPM Scythe Slip Stream (SSS?) starts fine a 5v -- and it is very slightly slower/quieter/less air than the SSS 500RPM at 12v. It blows more air at 12v than a GlobalWin NCB does at 5v; though it is also a bit noisier, too. (The GW NCB has the lousy "parallel" struts, btw...and it makes a much lower pitch noise than the SSS.)

At 5v, the 800RPM SSS and the 1300RPM GW NCB are blowing a very similar amount of air, and the SSS is slightly quieter. The GW NCB sound is dominated by the low pitch blade/strut noise (kind of a constant "purring"), while the only noticeable sounds from the SSS is some very soft bearing "ticks" -- probably when I move it. Each has the whoosh of air flow, of course. Since the GW NCB is too loud at 12v anyway, the SSS is the quieter fan and more useful fan from 5-12v.

The 500RPM SSS won't start at 5v, nor will it start at 7v. But again, it is so quiet at 12v, and frankly is probably only useful at 12v. At 5v (after bump starting it) it barely turns. At 7v the air flow is pretty feeble, though maybe as an intake fan blowing over an HD -- it is so quiet at 12v though, it really only makes sense to use it this way?

Conclusion: no, the 800 model doesn't fall over itself undervolting, so I should get the 800

. The S-flex, FI, had one, I think the 1600 RPM model, which was worse when undervolted, including not running as low, than the standard model of that lower speed.

Starting at low voltage isn't a problem. I only recently threw away my first kickstarter (tube relay, dead-bug RC circuit, rubber band holding it together). I plan to make one with a PICAXE, ASAP, now. I was actually hoping to mess w/ PWM fans (link), but if I do, it looks like I'll have to do that without any other real goal in mind. Or, you know, Scythe could make a 1200 RPM Slipstream PWM fan...

On the kick-start: you can go find fan controller ICs that will do it all, and they are cheap ($2-3 in single-unit quantities--so negligible when bought by the palette and compared to other costs of a fan, I imagine).

Cerb · Post by **Cerb** » Thu Nov 22, 2007 4:18 pm

I've now got a 800 RPM model as my CPU fan (two open windows in the room will have to do case cooling!), and...wow. This fan may be less than ideal not being a PWM fan, but it beats the Nexus silly at 12 volts. At three feet, ambient noises, like the wind in the trees, totally drown it out after about 3 feet. It pushes a decent amount of air, too.

It's doing just as good as Felger Carbon made it seem like it would.

I'll remain a TR fanboy for heatsinks (I'm already second-guessing my Ninja decision!), but Nexus has some serious competition now on the fans, and it's highly available (unlike, say, GlabalWin).

Big thumbs up to Scythe for these fans.

sea2stars · Post by **sea2stars** » Thu Nov 22, 2007 10:48 pm

Agreed. Now that I've got my main system back up and running again I'm really enjoying these fans. My temps are a tad higher compared to using the Globalwins, but the perceived sound is easily half that of the previous fans.