Pros: - What RM said is important. Applying this to the card, it can fill those little, itty-bitty PCI-e 1x slots on your motherboard because it is a PCI-e 1x card.
- Works with NAS4Free and have used it recently, fully loaded in an 11 HDD NAS. I have encryption, ZFS RAIDZ1 and ZFS compression all on four green WD 2 TB HDDs through this card [<rant>Why spend more on red WD HDDs when green WD HDDs on a home NAS are just fine? Notice I said home? Have been running green WD HDDs for nearly 10 years in 24/7 NAS' [I have four] and no issues but lower electricity bills.</rant>)
- SATA 6 GB/s
- Supports port multipliers (but I've never tried it)

Cons: - I always connect the SATA card I have in my NAS' to the power LED of the computer case so I can see HDD activity. Thus the case HDD light is for a 6x HDD RAIDZ1 array connected to the motherboard (has 6 SATA connectors) and the Syba SI-PEX40064 connects a 4x HDD RAIDZ1 array to the case power LED. The con is I had to solder in paperclip wire to the card's HDD activity connection to connect the case' power LED connector and what is seen is an always on light that blinks when there is activity. Typically a HDD light is off and turns on during activity only (not just blinks). The case LED now shows me power AND the 4x HDD array activity. Super minor con, I admit, I wish there were pins for those case LED connectors.

Other Thoughts: - Have had the card for years and works everywhere. Most importantly it has always worked with NAS4Free with all kinds of green WD HDDs.

Pros: 1. Customer support (I got email addresses of 5 people in their company!; they took time to remote access my NAS to see issues) 2. Does many things only a full computer can do (at a much lower power output, 36W). 3. Quiet. 4. Can connect many HDDs (I have connected four 500 GB HDDs). 5. Firmware is Linux-based (3rd parties added MySQL capability for example). 6. Mirroring of internal HDD (they call it QRAID and it's much more stable nowadays).

Cons: 1. Cannot write to NTFS drives (their new TS-109 Pro can! Newegg.com please stock this!), only read. 2. It's microprocessor is slow when doing more than one function (their new TS-109 Pro is faster!) 3. Gets too hot to touch (but their testing shows HDD not too hot [I am a test engineer in RL and I approve of their testing method]). 4. Early, buggy software issues adequately being addressed with regular firmware updates (your mileage may vary). 5. Some network, OS & PC knowledge to use effectively.

Other Thoughts: This device is very complicated so I cannot fit everything in this review. Compared to what is selling now, this unit scores high IMO. I have used this NAS in every iteration except as an iTunes server (Apple, yech!), Disaster Recovery (I have only one TS-101) and as a Print Server. Everything else (including Telnet) just works. As it's in a home it's not often that more than one function at a time is used. Firmware upgrades are regular and so far all have some increased functionality as well (interpret as "something more for what you already paid for"). Looking forward to TS-109 Pro which is faster and can do more functions silmultaneously.