How we measure power draw and motor power
We were very excited to see the results of the Grand Tornado 120. It looks good geometrically and is also one of the cheapest LCP models out there. Scythe has also informed us that the Grand Tornado 120 is set to outperform the legendary Gentle Typhoon (D1225C). And it’s true, it does outperform it, though perhaps in different ways than you’d expect. But the LCP fan from Scythe gets along really well with radiators.
How we measure power draw…
Is it worth addressing the power draw of fans? If you have seven of them in your computer (three on the radiator of the cooler and four for system cooling in the case) and they are also backlit, the power draw starts at tens of watts. This makes it worth dealing with.
All fans are powered by Gophert CPS-3205 II laboratory power supply. It is passive and virtually noiseless, so it does not distort our noise level measurements. However, for the PWM fans, a Noctua NA-FC1 controller is connected through which the fans are regulated. We also have a shunt between the power supply and the Noctua controller. On it, we read the voltage drop, from which we then calculate the current. However, the voltage on the power supply is set so that 12 V goes to the Noctua NA-FC1. We then also set the exact 12 V to measure the maximum power of the 3-pin linear power supply fans.
In the power draw tests, we will be interested in the power draw in fixed noise level modes in addition to the maximum power consumption at 12 V or 100% PWM. That is, at those settings at which we also measure other parameters. Finally, in the graphs you will also find the power consumption corresponding to the start-up and minimum speeds. The difference between these two settings is that at start-up speed you need to overcome the frictional forces, so the power draw is always higher than at minimum speed. At these, the fan is already running and just reduces power to just before a level where it stops.
These start-up and minimum power draw data are a substitute for the start-up and minimum voltage information. You often encounter this when reading about fans, but with PWM fans there is no point in dealing with it. And although it is possible to power a PWM fan linearly, it will always perform better with PWM control – lower starting and minimum speeds. Therefore, it would be unfair to compare these parameters for all fans using linear control. That way, fans with PWM would be disadvantaged and the results distorted.
…and motor power
In addition to power draw, it is important to consider one more parameter that is related to the power supply – the power of the motor. This is usually listed on the back on a label and is often mistaken for power draw. However, the voltage and current indication here is usually not about power draw, but about the power of the motor. The latter must always be well above the operating power draw. The higher it is, the longer the life expectancy of the fan.
Over time and with wear, fan friction increases (through loss or hardening of the lubricant, dust contamination or abrasion of the bearings, etc.). However, a more powerful motor will overcome the deteriorating conditions of the fan to some extent, albeit at a higher power draw, but somehow it will cope. However, if the difference between the motor power and the operating power draw of a new fan is small, it may no longer be able to exert sufficient force to turn the impeller under increased friction due to adverse circumstances.
To test the power of the motor, we set the fan to full power (12 V/100 % PWM) and increase the mechanical resistance by braking the impeller in the middle. This is a higher load for the motor, with which the power draw naturally increases. But this is only up to a point, until the impeller stops. The power of the motor in our tests corresponds to the highest achieved power draw that we observed when the fan was being braked.
We use the Keysight U1231A high sample rate precision multimeters to analyse motor power (as well as normal operating power draw). In addition, the individual samples are recorded in a spreadsheet, from which we then graph the maximum. The final value is the average of three measurements (three maximums).
- Contents
- Scythe Grand Tornado 120 in detail
- Overview of specifications from the manufacturer
- Basis of the methodology, the wind tunnel
- Mounting and vibration measurement
- Initial warm-up and speed recording
- Base 6 equal noise levels...
- ... and sound color (frequency characteristic)
- Measurement of static pressure...
- ... and of airflow
- Everything changes with obstacles
- How we measure power draw and motor power
- Measuring the intensity (and power draw) of lighting
- Results: Speed
- Results: Airflow w/o obstacles
- Results: Airflow through a nylon filter
- Results: Airflow through a plastic filter
- Results: Airflow through a hexagonal grille
- Results: Airflow through a thinner radiator
- Results: Airflow through a thicker radiator
- Results: Static pressure w/o obstacles
- Results: Static pressure through a nylon filter
- Results: Static pressure through a plastic filter
- Results: Static pressure through a hexagonal grille
- Results: Static pressure through a thinner radiator
- Results: Static pressure through a thicker radiator
- Results: Static pressure, efficiency depending on orientation
- Reality vs. specifications
- Results: Frequency response of sound w/o obstacles
- Results: Frequency response of sound with a dust filter
- Results: Frequency response of sound with a hexagonal grille
- Results: Frequency response of sound with a radiator
- Results: Vibration, in total (3D vector length)
- Results: Vibration, X-axis
- Results: Vibration, Y-axis
- Results: Vibration, Z-axis
- Results: Power draw (and motor power)
- Results: Cooling performance per watt, airflow
- Results: Cooling performance per watt, static pressure
- Airflow per euro
- Static pressure per euro
- Results: Lighting – LED luminance and power draw
- Results: LED to motor power draw ratio
- Evaluation
DNF at the very high target of 31dB(A) means it isn’t cheap, it means no matter the price it’s too expensive
additionally knowing it starts at around 680RPM and it still doesn’t pass that target means it’s just bad acoustically
it may find a niche, people are frequently mentioning this or that dethroning Noctua while the performance is only slightly higher at one very specific and extremely high noise target so at some point it may be a decent option, but I just wouldn’t bother, no reason to stand that noise when I can just set A12x25 a tiny bit below this ones starting speed and have it perform better and stay silent
This is subjective. It depends on who is looking for what. If the priority is the highest possible airflow regardless of noise level, while also weighing low vibration or extra durability, then the Grand Tornado 120 can be a great choice. In the context of that potentially high durability (if Scythe doesn’t exaggerate the MTBF value…), we also discussed the server concept of the Scythe Grand Tornado 120 fan in the discussion below the text in another language…
for separate-room-home-server I’d likely go with Noctua PPC or T30 (or NH-P1 due to superior reliability if the heat load was lower, though AC has the advantage of providing a decent heatsink that will prevent your system from shutting down even if fans stop, LC on the other hand…), for regular server room with regular server fans like Delta
for living/working space silence is a requirement impossible to give up on so the silent performance is all that matters
I really love its name (GT), indicating the intention for it to succeed Gentle Typhoon. Unfortunately, I don’t think it’s worthy of that title. Even if the argument is that it’s better in peak performance, remember there’s the GT-HI (https://www.e-jpc.com/wp-content/uploads/gentle-typhoon-d1225cen-2.pdf) that goes up to 5400 RPM!