Japan Servo
Japan Servo, Servo, and Nidec Servo are brand names associated with the Nidec Corporation, or Nihon Densan Kabushikigaisha.
Nidec SCNDM12B4
I found this fan at a sort of surplus outfit.
Link:
http://www.mpja.com/prodinfo.asp?number=18015+FN
They call it a "Square/Round fan," and I suppose it is: the exhaust side is a standard 120mm frame, while the intake side is a five-inch ring.
Image: Nidec SCNDM12B4, exhaust view
Image: Nidec SCNDM12B4, ring view
For six bucks, it was an easy fan to order. When I got my first copy, I loved it. I had to get another.
Image: Japan Servo SCNDM12B4, intake & exhaust views
Image: Japan Servo SCNDM12B4, facing up and down
Image: Japan Servo SCNDM12B4 on Megahalems - ready
Image: Japan Servo SCNDM12B4 on Megahalems - running
Image: Nidec SCNDM12B4 mounted on Megahalems
Note that Megahalems 38mm clips mount this just fine, because the clips grab onto the outside of the fan, not the inside. OTOH, mounting a second fan on the exhaust side is a bit of a stretch because the ring is too big to fit into recesses designed to accept 120mm frames; so it is held to the outside of the fin stack. But the clips just do get into their indentations and hold the exhaust fan on the cooler.
Nidec SCNDM12B4 Specs (a.k.a. - Six Dollar Servos)
(also, see pdf here:
http://www.japanservo.co.jp/digital/.../pdf/SCNDM.pdf)
Size: 120x38mm, 7 blades
Bearing: ball
Speed: 2650 RPM
Airflow: 106 CFM
SPL: 40 dBA
Static Pressure: 6.6 mm H2O
Features: Intake side has 5-inch ring; two wires, so no RPM reporter lead.
Results on the Megahalems (average):
Speed: 2470 RPM (estimated rpm by synchronizing another fan with it)
CPU temp over ambient: 51.5c
SPL: 39.5 dBA
In other words, it is a dead match for the San Ace -H101
Results on the Megahalems (#2 fan) at 5v:
Speed: 1095 RPM (estimated rpm by synchronizing another fan with it)
CPU temp over ambient: 58.5c
SPL: 19.5 dBA
This lets you know what the fan is like when it is not working hard. Unfortunately, it clicks. It clicks softly, so you might not hear it. After all it is under 20 dBA and it is inside the case.
Results on the Megahalems 12v, tandem mount (2 fans):
Speed: 2410 RPM (average) (estimated rpm by synchronizing another fan with each fan)
CPU temp over ambient: 49c
SPL: 41.5 dBA
"Smooth for the work."
Really excellent results.
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Japan Servo Centaur - CNDC12Z7RP
Another "surplus" fan, this time only five bucks (link:
http://www.mpja.com/prodinfo.asp?number=18222+FN)
Image: Japan Servo CNDC12Z7RP, intake & exhaust views
Link:
http://www.japanservo.co.jp/digital/...l/pdf/CNDC.pdf
Japan Servo CNDC12Z7RP Specs:
Size: 120x38mm, 7 blades
Bearing: ball
Speed: 3200 RPM
Airflow: 124 CFM
SPL: 49 dBA
Static Pressure: 10.7 mm H2O
Features: Vendor copy says 3d wire is stall sensor. Wrong: 3d wire is RPM reporter.
Results on the Megahalems:
Speed: 3050 RPM
CPU temp over ambient: 50c
SPL: 46 dBA
No advantage over the San Ace -H101, and a lot more noise. Yet a good cheap fan for radiators.
Results on the Megahalems at 5v:
Speed: 1590 RPM
CPU temp over ambient: 52.5c
SPL: 29.5 dBA
At 5 volts, this is a pretty decent fan for $4.95US. It's nearly as good as a number of expensive fans, better than most and is pretty quiet. But you must keep it on a leash.
Tandem fans - Results on the Megahalems at 12v:
Speed: 3110 RPM (average)
CPU temp over ambient: 48.5c
SPL: 50 dBA
"They sing!"
Tandem fans - Results on the Megahalems at 5v:
Speed: 1590 RPM
CPU temp over ambient: 52c
SPL: 33 dBA
Essentially the same temps as a solo fan at 5v, but more noise.