I've been monitoring SMART temps a few hours before setting up the 4x HD501LJ RAID-0, as the ICH8R RAID controller won't pass the SMART values (as opposed to some hardware RAID controllers), so I spent the first day monitoring temps while I still could.
I got 38~42°C while all drives were mostly idle but the CPU was running at ±100% usage on both cores in a CPU benchmark for about one hour. Then, simultaneously running four HDD benchmarks on all four 501 for about three hours (in order to simulate a heavy HD video editing work) and still running the CPU benchmark, gave 45°C~48°C for three 501 drives that are located in the upper front of the server tower, while the one sitting in the lower front (next to both HD401LJ drives) gave 44°C~45°C; the lower region benefits from a better airflow. All tests done in a 20°C~23°C ambient room.
At the end of this three hours period, my moderately (3.40 GHz instead of 2.67) overclocked Conroe E6700 was ~72°C on both cores, while global CPU temperature was reported ~61°C; it's cooled by a passive Scythe Ninja, the single fan in the rig is a 120mm Nexus softmounted at the rear next to the Ninja and rpm-controlled by the motherboard (~600rpm in CPU-idle and ~1000rpm max in long CPU benchmarks). The PSU is a fanless Yesico 550W; the GPU is a fanless 7600GT. Gigabyte 965P-DQ6 motherboard.
My conclusion was that HDD temps would be ok in any situation with this single-fan setup, but I was a little afraid about the CPU temps (and power regulators located near the CPU socket too) so I downgraded the overclocking to 3.20 GHz, and lowered CPU voltages accordingly, as much as I could without creating instability. This resulted in a ±6°C gain on CPU temps.
I must say that this rig is both the most powerful and the quietest amongst the 6 computers I'm using for my work. Two years reading SPCR reviews and forums, buying and testing all sorts of components, made the job. Now obviously I could mod/rebuild all other PCs accordingly to what I've learned, but I think I'll just quieten each one when upgrading it. The loudest three are now in another room where I don't stay for long, and I spend most of the time using only the Conroe, as anything else producing some noise easily gets me irritated. Well yes, that's the bad side of reading SPCR
I would advise you to start with a single HD501LJ or HD160HJ in a decoupled Scythe Quiet Drive. I've been reading too many bad reports on the HD321KJ, and we still don't know for sure if it's always 2-platter, always 3-platter or a mix. If you're using more than one HDD in your rig, make sure to fully decouple both from the tower. You can gain some space by removing the lateral metallic plates on the Scythe boxes. Make sure to leave absolutely no air bubbles under the gel sheets while placing them to both sides of the internal metal cage of the Scythe box. Then check if your computer using habits would benefit from a two-drives RAID-0 as the userfiles partition (don't do it for your boot drive, you won't gain much anything).
. Last step was of course, finding the quietest HD drive. Samsung's 2.5 5400 RPM 80gb trully made my computer inaudible.
