Couldn't find stock of the MA74GM-S2 so ended up with a MA74GM-S2H (quite a bit cheaper than my MA78GM-S2H used in my HTPC - so no point paying over the odds) as part of a bulk eBuyer purchase. Delivered this morning - time from delivery to file transfer was less than 90 minutes. Never built a system in an ATX case before - so nice to have room! (All my previous PCs have been compact HTPCs where everything is really fiddly and cable management is a nightmare. So nice to be able to neatly tie-wrap everything easily for a change!)
The system is mounted in a Cooler Master Centurion 5 with Cooler Master Extreme Plus 550W PSU, I'm using 2Gb of Kingston 5400 / 667MHz RAM, and an AMD LE-1640 CPU with stock heatink and fan. Hard drives are Samsung Spinpoint F1s - 1TB and 500GB currently which I had spare. Not yet put in a parity drive. Using a 1GB Lexar Firefly (as recommended) as the USB boot disk, with BIOS configured to boot from USB-HDD running the Free version, just to check things out. Have switched on AHCI support and disabled all the on-board stuff that UNRAID doesn't use (Audio, floppy etc.). Have still connected the audio headers to the case - well it gives them somewhere to go... Haven't even bothered bunging in an optical drive.
Connecting via Gigabit Ethernet to my MA78GM-S2H-based HTPC I'm getting around 45-50MB/sec transfers - both large ISOs and a bulk transfer of lots of 320k MP3s and Apple Lossless stuff. This appears to be completely respectable (I was getting around 60-70MB/s SATA to SATA transfers within the HTPC, and compared to the 20MB/s I get with a USB2 external it is a major improvement!)
Centurion 5 with 550W PSU was a reasonably cheap bundle - may regret it as it only has 5 exposed 5.25" drive bays - so I can only use a 4-in-3 and a 3-in-2 if I get ambitious, and won't be able to use two 4-in-3s - but that would still leave me with 11 drives - which may be too many for the PSU anyway... However at the moment I suspect I'll be fine! (No problems with fitting 6 drives - which is my motherboard SATA limit)
Obviously it has only been running for a couple of hours and I'm not running with a Parity drive yet, - heck I haven't screwed the side on - but I'm really chuffed at how easy it was. (And VERY impressed at the boot from USB with no requirement for a lengthy OS install)