Removing the thumbscrews also frees the case cover, which easily lifts off. Figure 4 shows the 5500's innards with everything on the main board nice and accessible without requiring further disassembly.
Figure 4: N5500 inside view
Figure 5 shows a better view of the main board. The 1.86GHz Intel Celeron M processor (same as used on the N7700) is under one of the heatsinks, and I suspect the North and South bridges are under the others.
You can see the single SODIMM of 1 GB of DDRII 800 RAM. Even though there is an empty slot, Thecus does not want you upgrading RAM on your own and doesn't offer a RAM upgrade option.
Figure 5: N5500 board
The "Dual DOM" feature that is a major marketing point for the 5500 is at the bottom right of the photo. It's actually two 128 MB IDE Disk on Memory (DOM) boards. The Dual-DOM feature is supposed to automatically switch to the second DOM module in case the first one fails, providing increased reliability.
I'm skeptical of the value of the Dual-DOM, given that flash memory modules aren't high-failure items. A more useful feature would be the ability to store two firmware versions, as some business-class routers allow. This allows fallback to a previous firmware revision in case you find something wonky with a new one.
I didn't test to see whether the dual-DOM worked, but the guys over at ITPro did. They found that the system switched over fine to the backup DOM when they pulled the connection to one of them. But while the system provided access to all the folders and shares, they found that "a number of network services had stopped and all users, groups and AD settings were gone".
Moving along, the dual Gigabit Ethernet ports are provided by two Intel WG82574L PCIe Gigabit Ethernet controllers, again, the same as the N7700. But the 5500 uses two Silicon Image Sil3132 PCI Express to 2-port Serial ATA (SATA) II host controllers instead of the two Marvell 88SE6340 PCIe 3 Gbps SAS/SATA 4 port controllers on the N7700. The USB ports are provided by a Plx NET 2282 PCI to High-Speed USB 2.0 Controller.
The drive bay supports five hot-swappable 3.5" SATA drives. Thecus hasn't yet posted the drive compatibility list (it's due up soon). But they sent three WDC WD1600AAJS-0 160 GB Caviar Blue and two Seagate ST380815AS 80 GB 7200.10 drives in the review unit. This made for a total power draw of 54 W with all drives spun up.
Updated 8/15/2009: Drive spindown works.
Although you can set an idle drive spindown time
from 30 to 300 minutes of inactivity (30 minute increments), I never saw the drives spin down, even when I pulled the network connection.
You can set an idle drive spindown time from 30 to 300 minutes of inactivity (30 minute increments), which reduces power consumption to 30 W. You can also schedule different power on/off times for each day of the week.
I'd rate the 5500's noise level as high, with most of it coming from fan noise. It's certainly doesn't scream like a rackmount server. But you'll definitely know that it's on, even if you have other relatively noisy systems running. I also heard the occasional cabinet buzz, which I was able to silence by opening the front cover and gently wiggling the drives a bit.