Hello everybody!
Recently, I built a very small NAS. Due to my high electricity costs I simply had to change something, my big home server with 10 HDDs needs too much juice...including the UPS about 180W idle.
So created this system:
AsRock AM1B-ITX
AMD Athlon 5350 @2.05Ghz
8GB RAM
2x Seagate ST4000LM016 (2x 4TB, RAID0 with ZFS)
1x Crucial M4 128GB mSATA
OpenMediaVault 2
The case I used is a Chieftec IX-01B. A very cheap and cool case, but unfortunately, it's only for drives with standard size. The height of the Seagate HDDs is 15mm, not 9mm like other 2.5" drives. Another problem, you can only use very thin CPU heatsinks.
Chieftec says, you can use 40mm heatsinks, but you have to subtract the drive's height. So in my case, there are only 25mm left for the heatsink. The boxed cpu cooler is about 22mm high plus the fan's height of 10mm, there are only 8mm left.
But this wasn't the biggest problem. The HDDs are too high (about 3mm), so one of them was touching the RAM and as mentioned before, the other one collided with the cpu cooler.
So I did some DIY work on that 
I had an Aluminium heatsink with dimensions of 90mm x 90mm x 15mm in my junk box. I just tripped two parts to make it fit in and cut two M4 threads into it for mounting. After that, I made a 2mm thick Aluminium plate for mounting the HDDs in a way, they would fit in perfectly.
Finally, I could place two HDDs and one mSATA SSD (stuck between one HDD and the cpu cooler) in the case.
Everything is running very well, the two Titan TFD-5010M12Z case fans are pretty silent if cpu is in idle.
