As I cannot use the unit's thermocouple to determine the temperature of the hard drive, I used an IR temperature sensor instead.
Intel Pentium 4 2533MHz
ASUS P4S533 Motherboard
Maxtor 80GB 7200RPM ATA133 Hard Drive
Running Windows XP Professional
All inside an Aspire Turbo Gamer case, system fans OFF
For the idle temperature, I let the system idle for at least 30 minutes. For simulating hard drive load, I used SiSoftware Sandra's File System benchmark test. For my particular setup, I noticed the thermocouple temperature rise from 26°C to 29°C, and the speed of the fan from 2700RPM to 3800RPM during the load simulation.
Some pretty nice results here. In both idle and load moments, the difference is around 8° Celcius. Fan noise was negligible as well, as I did not notice any significant increase in noise. Very well done here.
While the unit excels at its job of keeping the hard drive temperatures lower than usual, its installation annoyances greatly detract from the overall experience of the product. A longer thermocouple (or one that is connected to a cable) would've allowed the user to relocate it to a hotter spot on the hard drive. However, a hard drive rack also has a secondary use: It allows the user to swap drives without needing to open the case - definately useful as an emergency hard drive bay, or a great way to test a friend's hard drive without having to open up your own case, provided that your primary drive is not using it already. So even if additional hard drive cooling is not your primary concern, if you find yourself swapping hard drives alot, consider using this unit to help you with your swapping tasks.
Cools the hard drive effectively.
Can act as a simple method of exchanging hard drives without opening the case.
Thermocouple can only monitor the housing's ambient temperature
Housing lid can be shut "permanently" if the hard drive is not properly secured.