Scythe: Kama or Slipstream?

KayDat · Post by **KayDat** » Tue Aug 31, 2010 10:08 am

Looking at grabbing a PWM fan to use with Accelero S1/5870 combo, so I can control the fan via software. Was wondering what are the characteristics of each fan? A quick read of Fan Roundup 5 (which doesn't have the PWM Slipstream, but I assume its somewhere between the M and H models in terms of acoustics) didn't reveal that much other than the fact that Scythe fans are fairly quiet.

bozar · Post by **bozar** » Tue Aug 31, 2010 11:31 am

The PWM Slipstream are reviewed in several CPU cooler reviews here such as Mugen 2 and Ninja 3. I do think Slipstream is smoother but they seem to wear-out quicker then a Kama fan, the later seems a bit higher in quality.

I don't think the idea is a great one though, the motherboard will react to the very high amount of heat and let the fan go out of control. PWM fans are not quiet at full speed, nowhere close to quiet.

lodestar · Post by **lodestar** » Tue Aug 31, 2010 12:14 pm

There are several models of SlipStream PWM fans. The SY1225SL12LM-P is the one fitted to the Mugen 2, and has a roughly 300 to 1300 rpm range. The one fitted to the Yasha and Ninja 3 has adjustable PWM ranges, from about 400 to 1300 rpm on Low to around 740 to 1900 on High. This fan, the SY1225SL12HPVC, comes with a PCI slot controller allowing you to set the PWM range to Low or High or any point in between. What it means effectively is that you can set the fan idle speed to where you want, and allow the PWM control to react to changes in load by speeding up or slowing down the fan speed. You can combine the fan controller with software control if required. As PWM control is thermal it will react not only to hardware heating up/cooling down as load is applied/removed but to ambient temperature as well.

I have both but would lean towards the adjustable PWM model because it is more flexible. Used as a CPU fan it is certainly possible to set idle speeds as low as 500 rpm but under load not see much over 1100 rpm. For software control I have found CPUID HWMonitor Pro works well.

KayDat · Post by **KayDat** » Tue Aug 31, 2010 10:47 pm

Thanks for the info guys, but...what's the difference between the two? 7 fins vs 9 fins, broad fins vs narrow fins? Do either one have a preferred function? i.e. case fan vs heatsink fan.

@bozar
I'll be hooking the fan up to my gfx card, and controlling the speed via software (MSI Afterburner, to be exact), so it won't be going out of control. Even so, if there was high amounts of heat in a system, I'd say that something isn't right, and the fans should be spinning up anyway, to avoid hardware failure.

@lodestar
Well, the product description at PCCG claims:

This 120mm SlipStream PWM fan offers 0 ~ 1300RPM for 0 ~ 26.5dBA & the maximum achievable airflow is 74.25CFM at the full 1300RPM.

I wonder about the 0RPM claim, since PWM fans typically can't actually stop without a change in voltage, so I'm assuming that it's the SY1225SL12LM-P you mentioned that is paired with the Mugen 2.

Parappaman · Post by **Parappaman** » Wed Sep 01, 2010 1:32 am

Do you already have the S1 on hand? If not, you should really consider getting a TwinTurbo Pro instead. Costs just a bit more, and comes with two excellent PWM fans that you can control via the 5870 fan header. Plus, it's smaller, easier to mount and probably better performing than the S1 with a single fan strapped on it.

KayDat · Post by **KayDat** » Wed Sep 01, 2010 1:56 am

Parappaman wrote:Do you already have the S1 on hand? If not, you should really consider getting a TwinTurbo Pro instead. Costs just a bit more, and comes with two excellent PWM fans that you can control via the 5870 fan header. Plus, it's smaller, easier to mount and probably better performing than the S1 with a single fan strapped on it.

Yep, I have an S1 already. Bought it off ryboto back in April in the Classifieds section here for $30 shipped with a regular Slipstream fan, which is much cheaper than what the TTPro costs in Australia. I'm fairly happy with it overall (aside from wanting automatic speed control), except when it is heavily loaded (e.g. OCCT); I find that there is a nasty heat build up then, which I assume means the S1 is barely adequate for the 5870. At idle and regular loads, the S1 is cooler and much quieter than the stock cooler.

Parappaman · Post by **Parappaman** » Thu Sep 02, 2010 12:00 am

The S1 vomits all of the video card heat inside the case, so it needs good case airflow.
You may try 2x Arctic F2 PWM 92mm, you get better airflow coverage on the card than if using a single 120mm unit. They can be daisy chained on a single PWM header, are cheap, reliable and of good quality. They also slow down nicely, I have one in my case right now spinning at just 600 RPMs and is inaudible up to 900.

GHz · Post by **GHz** » Fri Sep 03, 2010 2:41 pm

The FDB Kama series is probably a better bet for cooling a video card. They stand up to heat better. Nevertheless, the PWM Slipstream is very good for a sleeve-bearing fan. I don't have a Kama on hand, but I do have various other Sony FDB fans for comparison. They are usually consistently good, except for the latest Thermalright that I got which has some highly directional motor noise. FWIW, I measured 28 dBA for the M model of the Slipstream and 68.4CFM. The small hub really helps with the airflow. For comparison, the Thermalright (same as Kama) at 819 RPM puts out 33 CFM compared to 38 CFM for the Slipstream at 733 RPM (<21 dBA).