Disclaimer: The results presented are an actual test performed on a fully loaded Dell Dimension 2350 system and are for informational purposes only. Adding any new components inside the case will increase power consumption and your results may vary based on your system's configuration and use. iResolved cannot be held responsible for any damage done to the system. That stated... 

Summary

This test was conducted to determine the heating effect of adding a third hard drive into the system. As expected the drive temperatures increased by 3 degrees Celsius (5.4 deg F), but are still well within the recommended operating range of hard drives. As suggested below, the least used or backup drive should be placed in the center position.

Setup

Equipment

• Dell Dimension 2350: a stock computer with three hard drives configured as shown on the right with round IDE cables, two DVD-RWs, and all three PCI slots filled, one with the IDE controller card described below.

• IDE controller card: Ultra ATA/133 IDE RAID PCI controller card with SI chipset controlling the 3rd drive only. Full specs here.

Software

• HDD Temperature: from www.hddtemp.com used to check the temperature of the S.M.A.R.T. technology enabled hard drives.

Process

1. Install HDD Temperature software

2. Bring the system to steady state temperature by running for at least 6 hours

3. Measure the temperature of the drive(s) and record

4. Install additional drive(s)

5. Bring the system to steady state temperature by running for at least 6 hours.

6. Measure and record the temperature of the drives.

Results:

All temperatures given in degrees Celcius. The arrangement of the hard drives in the table below matches the picture above. Room temperature was 21 degrees C.

Analysis:

The middle drive temperature increased by 3 degrees Celcius, and the primary drive nearest the front of the case showed no appreciable heat increase.

Conclusions and recommendations:

The middle drive temperature's increase is relatively small and within the recommended operating temperature of the drive. The recommended temperature varies by manufacturer, but is usually between 5-55 degrees Celcius with some newer drives operating safely up to 60 degrees. For instance, check these links to Seagate and Maxtor.

Since the middle drive is positioned between two other drives, it will receive less airflow, even though designed to increase exposed surface area. As such, it is recommended that lower RPM drives or lesser used drives are placed in the middle and that the temperature is checked regularly.

Please contact me with your own results, questions, or additional links and comments. -alex@issue-resolved.com