Testing an active TEC CPU cooler is more challenging than testing a traditional HSF. As I mentioned earlier, the Monsoon II Lite active TEC CPU cooler isn’t designed for extreme overclocking, sub-zero temperature operations. It is a high-performance HSF that uses a medium size Peltier device to enhance the cooler’s overall cooling capabilities. The PCI card control module is programmed to maintain a target CPU temperature, which should never drop below 25°C. Initial tests using my standard test procedures at 24°C ambient room temperature, produced acceptable results but clearly not outstanding.
The key measure of a heatsink fan’s performance is how well it can cool the CPU. This is typically measured by subtracting the ambient air temperature from the CPU temperature, which results in a differential temperature (referred to as the Delta T). The closer the CPU temperature is to the ambient air temperature the better (smaller Delta T). And when some form of active cooling is employed, there is the potential for temperatures to drop below the ambient temperature (-Delta T).
The performance of most traditional heatsink fans and water-cooling systems that rely on convection cooling changes linearly with the ambient room air temperature (at least within the temperature range of most CPU operation). If the ambient air temperature goes up 10°C, then so will the CPU temperature (Delta T remains the same) and vise versa. However, with active TEC cooling this is NOT the case. To test the true potential of the Monsoon II Lite active TEC cooler required a slightly modified testing setup… 🙂
In this configuration, a 4” duct is used to route the warm exhaust air coming out the back of the Monsoon II cooler around to the front where it is sucked back in. By carefully positioning the duct, just the right combination of warm recycled air and cool ambient air can be mixed to simulate a much warmer operating environment. Doing this to a normal HSF would kill its performance, but when I fed the Monsoon II Lite warmer air, it resulted in better performance – not worse!
The Monsoon II Lite was tested on a red-hot Pentium 4 EE based test rig consisting of the components listed below. Four instances of CPUBurn were executed at the same time (two to load both physical cores, and two to load the two virtual HyperThreading cores), which resulted in 100% CPU usage.
Test Rig Configuration
- Asus P5N32-SLI Deluxe motherboard
- Pentium 4 Extreme Edition dual core 955 @ 3.46 GHz
- (2) Corsair CM2X512-8000UL DDR2
- nVIDIA 7800 GTX 512 MB video card
- Western Digital WD1200JD S-ATA HDD
- SilverStone Zeus ST75ZF 750W PSU
- Windows XP Pro with SP2
- nVIDIA 91.31 nForce driver
A small Omega thermocouple is attached to the side of the 955 IHS with Arctic Alumina thermal epoxy to provide accurate CPU temperatures. The measurement equipment used during testing included:
- CPU/IHS – Barnant Model 115 digital thermometer (accuracy +/- 0.4º C)
- Ambient air – Barnant Model 115 digital thermometer (accuracy +/- 0.4º C)
- Extech Model 407738 digital sound level meter (accuracy +/- 1.5 dB)
- Lavalys Everest Ultimate Edition 2006 (hardware monitoring)
- CPUBurn (load the CPU)
For comparison, I included the results from four other traditional, high performance HSFs for the LGA775 platform. All HSFs were tested on the same EE 955 CPU under the same conditions.
- Enzotech Ultra-X with 120mm Delta fan
- Thermaltake Big Typhoon VX
- Thermalright XP-120 with Antec TriCool 3-speed fan
- Thermalright Ultra-120 with Antec TriCool 3-speed fan
The following data is presented for comparative purposes only. Your actual results may be different depending on the variables unique to your system (CPU, overclock, ambient temperature, case air flow, temperature monitoring, etc).
Amb – Ambient room air temperature
CPU – Temperature reported by Everest utility (internal diode)
Tc – Temperature obtained with calibrated thermocouple attached to 955 IHS
∆T – Fully loaded Tc temperature rise above ambient temperature
dBA – Sound pressure level recorded 3’ away (background ~30 dBA)
Note: My original P5N32-SLI Deluxe motherboard died awhile back and the CPU temperature reported by the replacement board is so far off (~20°C) its not worth mentioning – the thermocouple attached to the 955 IHS is much more reliable.
(CPU/IHS Thermocouple) (Inlet Air Temperature)
The Monsoon II Lite cooler was tested on a fully loaded 955 Presler core at six different ambient air inlet temperatures. Normally the CPU temperature would go up proportionately to the ambient air temperature. But with the active TEC cooling locked in, the Delta T decreased as the inlet air temperature to the cooler increased. This illustrates the unique characteristic of the Monsoon II Lite active TEC cooler – it performs better as the ambient air temperature (internal case temperature) increases.
We saw this same trend almost a year ago when we tested the original Monsoon II cooler on an AMD Athlon64 3200+ (0.13 mm
(Test results from the original Monsoon II review, July 2006)
Note: The Athlon64 3200+ CPU doesn’t put out near as much heat as the dual core Presler 955, so at that time, the Monsoon II cooler was actually able to lower the AMD CPU temperature a few degrees below ambient.
Once again, I am impressed by how well the Monsoon II Lite active TEC CPU cooler performed. The Monsoon II Lite is far from silent but not as noisy as you might expect an air-cooled TEC cooler to be (50~60 dBA). Under load, the fan never seemed to slow down and the worst case was 43.9 dBA at high speed measured 3’ away with an ambient background noise level of 29 dBA.
The Monsoon II Lite is much better at dealing with high internal case air temperatures than a standard HSF thanks to the active TEC cooling. So bottom line, if you have relatively low ambient air temperatures (A/C) and good case cooling, then the Monsoon II may not offer any advantage over a good HSF. On the other hand, if you have above normal case air temperatures, then the Monsoon II CPU cooler may be just what you are looking for.