I used four Raptors for this test but they were all different models. The 150GB HDDs proved to be hotter than their 74GB predecessors on the open testbed.
The HDDs were installed in the following way: three of them occupied the three top seats in the main HDD rack (from top to bottom: Raptor WD740GD (the system disk), Raptor WD740ADFD and Raptor WD1500ADFD). The Raptor WD1500AHFD with a window in its case took its place in the top hot-swap bay.
Considering that the default configuration of the Hoplite leaves a lot of room for improvements in terms of cooling, I performed an additional test after such improvements. In its default configuration the Hoplite passed the tests at the minimum speed of its fans (“min” in the diagrams), but for the additional test I switched the front-panel fan to its full speed and installed a couple of 120mm fans (connected to the mainboard in Silent mode).
To be specific, I put an intake fan Thermalright TR-FDB-12-1300 (about 850 RPM in Silent mode) on the top seat on the side panel and an exhaust fan ExeGate 12025M12B/Blue LED (about 1400 RPM in Silent mode) on the top panel above the CPU socket (“max” in the diagrams).
Enermax Hoplite min
Enermax Hoplite max
You can note that the additional fans did not improve the cooling of the components. Their temperatures even increased by 1 or 2 degrees (this may be due to the inflow of hot air from the better-cooled HDD bay). So, you shouldn't bother about installing extra fans into this system case if you've got a PC configuration similar to mine.
It’s different with the HDDs. When the front-panel fan is switched from its minimum to maximum speed, the temperature of the HDDs in the main HDD rack declined from a dangerous to a more acceptable level (the temperature is going to be even lower if your HDDs are not as hot as my Raptors). The problem is that the fan is far from comfortable in terms of noisiness at its maximum speed (by the way, the ExeGate fan was much quieter at a similar speed).