Scythe Ninja

Heatsink Test – Joe

SUMMARY: Minimal fanless performance, excellent with 120 mm fan for Intel/AMD CPU cooling – with the right setup, can be both quiet and aggressive when needed.

Scythe Ninja

Size: 110 x 110 x 150 mm; Weight: 665 grams (ex fan).

The good guys at The Heatsink Factory were nice enough to send the latest Scythe heatpipe, the Scythe Ninja for a test spin.

The Scythe Ninja is designed to fit all known Intel P4 motherboards using the stock P4 heatsink retention bracket and AMD Sempron (socket 754), Athlon 64 (socket 754), Athlon 64FX (socket 754) all speeds Opteron (socket 939) and Opteron (socket 940).

Looking at this from the side

Scythe Ninja Front

shows why this large heatsink is also not unduly heavy – good fin spacing. Airflow from the fan will also cool downstream components – a real plus with this design. However, the one concern I would have is its height – a sharp jolt could exert a high level of force on the retention bracket (long lever arm).

The Scythe Ninja ships with parts for P4 and K8 mounting:


Included are wire clips to mount a 120 mm fan.

The base is so-so:


When I ran my nail over it, I could feel slight polishing ridges.


The Scythe Ninja was tested on an Acorp 4S845A motherboard with a modified P4 1500 to read CPU case temps. I tested the Scythe Ninja without a fan and then with an Adda 120 x 25 mm fan.

I varied voltages to get a performance range for various fan speeds, measuring rpms using an Omega digital tachometer. I measured fan noise with a Radio Shack sound meter 8″ from the fan’s intake. These are not comparable to noise levels reported by fan manufacturers; noise is usually measured at three feet from the fan.


Case Temp
Ambient Temp
Die Temp¹
Scythe Ninja, 2439 rpm, 61 dBA
30.6 C
23.1 C
Scythe Ninja, 1774 rpm, 52 dBA
31.7 C
23.2 C
Scythe Ninja, 1222 rpm, <50 dBA
33.1 C
23.4 C
Scythe Ninja, 938 rpm, <50 dBA
34.4 C
23.6 C
Scythe Ninja, 518 rpm, <50 dBA
39.1 C
23.9 C
Scythe Ninja, No Fan
58.8 C
23.8 C

¹Die Temp as measured by the P4 on-die diode, per MBM.

Interpreting C/W: For every watt (CPUw) that the CPU
consumes, the HSF will limit the CPU’s temperature rise to (C/W x CPUw)
plus the temperature at the HSF’s fan inlet. For example, at an ambient temp of 25 C, a C/W of 0.25 with a CPU radiating 50 watts means that CPU temp will increase 50 x 0.25 = 12.5 C over ambient temp, or 37.5 C. The lower the C/W, the better.

With a 120 mm fan @ 2439 rpm, the Scythe Ninja ranked near the top of P4 heatsinks tested to date (Heatsink Ranking).
Results place the fanless Scythe Ninja at the bottom rank of P4 heatsinks tested to date


Scythe’s Ninja with a 120 mm fan is an excellent choice for aggressive P4/K8 CPU cooling. However, the more aggressive the fan used, the higher the noise level – no surprise. A side benefit of using a fan with this heatsink is that airflow resistance is minimal – there is lots of cooling air coming through the fins to cool other components in its path.

Fanless performance is not for aggressive cooling; note that fanless performance will depend a great deal on case airflow – the more flow, the better performance, although it will not come close to performance with a 120 mm fan, even at very low rpms. Considering results, you’re better off with a minimal 120 mm fan than fanless; Under 1000 rpm, a 120 mm fan is just about silent.

If you want top performance while gaming but almost soundless at other times, I would recommend using an aggressive 120 mm fan with a rheostat – this gives you the best all-around performance capability. For “normal” use, a fan spinning at about 1700 rpm will give very good performance at low noise levels.

Thanks again to The Heatsink Factory for sending this our way. The Scythe Ninja is available now for purchase.

Disclosure: Joe Citarella has a financial interest in a company developing thermosyphon products for electronic chip cooling.

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